Add metadata code that is removed from core

[christian-monch]

Fixes #62

This PR adds the metadata code from datalad-core, which is deprecated.

It is tested against the datalad commit ff0f6a71b460075b7aa85a9da8052ab570f04590

[codecov-commenter]

Codecov Report

Base: 89.50% // Head: 56.52% // Decreases project coverage by -32.98% :warning:

Coverage data is based on head (b971f98) compared to base (fb171bd). Patch coverage: 22.76% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #63 +/- ## =========================================== - Coverage 89.50% 56.52% -32.99% =========================================== Files 22 57 +35 Lines 2831 5380 +2549 =========================================== + Hits 2534 3041 +507 - Misses 297 2339 +2042 ``` | [Impacted Files](https://codecov.io/gh/datalad/datalad-deprecated/pull/63?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad) | Coverage Δ | | |---|---|---| | [datalad\_deprecated/\_\_init\_\_.py](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad#diff-ZGF0YWxhZF9kZXByZWNhdGVkL19faW5pdF9fLnB5) | `100.00% <ø> (ø)` | | | [datalad\_deprecated/metadata/extractors/annex.py](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad#diff-ZGF0YWxhZF9kZXByZWNhdGVkL21ldGFkYXRhL2V4dHJhY3RvcnMvYW5uZXgucHk=) | `0.00% <0.00%> (ø)` | | | [datalad\_deprecated/metadata/extractors/audio.py](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad#diff-ZGF0YWxhZF9kZXByZWNhdGVkL21ldGFkYXRhL2V4dHJhY3RvcnMvYXVkaW8ucHk=) | `0.00% <0.00%> (ø)` | | | [datalad\_deprecated/metadata/extractors/base.py](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad#diff-ZGF0YWxhZF9kZXByZWNhdGVkL21ldGFkYXRhL2V4dHJhY3RvcnMvYmFzZS5weQ==) | `0.00% <0.00%> (ø)` | | | [...lad\_deprecated/metadata/extractors/datalad\_core.py](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad#diff-ZGF0YWxhZF9kZXByZWNhdGVkL21ldGFkYXRhL2V4dHJhY3RvcnMvZGF0YWxhZF9jb3JlLnB5) | `0.00% <0.00%> (ø)` | | | [...d\_deprecated/metadata/extractors/datalad\_rfc822.py](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad#diff-ZGF0YWxhZF9kZXByZWNhdGVkL21ldGFkYXRhL2V4dHJhY3RvcnMvZGF0YWxhZF9yZmM4MjIucHk=) | `0.00% <0.00%> (ø)` | | | [datalad\_deprecated/metadata/extractors/exif.py](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad#diff-ZGF0YWxhZF9kZXByZWNhdGVkL21ldGFkYXRhL2V4dHJhY3RvcnMvZXhpZi5weQ==) | `0.00% <0.00%> (ø)` | | | [...ed/metadata/extractors/frictionless\_datapackage.py](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad#diff-ZGF0YWxhZF9kZXByZWNhdGVkL21ldGFkYXRhL2V4dHJhY3RvcnMvZnJpY3Rpb25sZXNzX2RhdGFwYWNrYWdlLnB5) | `0.00% <0.00%> (ø)` | | | [datalad\_deprecated/metadata/extractors/image.py](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad#diff-ZGF0YWxhZF9kZXByZWNhdGVkL21ldGFkYXRhL2V4dHJhY3RvcnMvaW1hZ2UucHk=) | `0.00% <0.00%> (ø)` | | | [datalad\_deprecated/metadata/extractors/xmp.py](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad#diff-ZGF0YWxhZF9kZXByZWNhdGVkL21ldGFkYXRhL2V4dHJhY3RvcnMveG1wLnB5) | `0.00% <0.00%> (ø)` | | | ... and [31 more](https://codecov.io/gh/datalad/datalad-deprecated/pull/63/diff?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad) | | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=datalad)

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[christian-monch]

crippled filesystems tests are addressed in PR #64

[christian-monch]

crippled filesystem tests are known to fail and removed in PR #64

[yarikoptic]

all metadata tests are simply skipped..

python -m nose --traverse-namespace -s -v -A "not (turtle)" --with-cov --cover-package datalad_deprecated ${DTS}
datalad_deprecated.metadata.extractors.tests.test_audio.test_audio ... SKIP
datalad_deprecated.metadata.extractors.tests.test_base.test_api_git ... SKIP
datalad_deprecated.metadata.extractors.tests.test_base.test_api_annex ... SKIP
datalad_deprecated.metadata.extractors.tests.test_datacite_xml.test_get_metadata ... PATH
create(ok): /home/appveyor/DLTMP/datalad_temp_tree_test_get_metadatanb1bwcwv (dataset)
PATH
create(ok): /home/appveyor/DLTMP/datalad_temp_tree_test_get_metadata2aaf8ilx (dataset)
add(ok): elsewhere/meta.datacite.xml (file)
save(ok): . (dataset)
action summary:
  add (ok: 1)
  save (ok: 1)
ok
datalad_deprecated.metadata.extractors.tests.test_exif.test_exif ... SKIP
datalad_deprecated.metadata.extractors.tests.test_frictionless_datapackage.test_get_metadata ... SKIP
datalad_deprecated.metadata.extractors.tests.test_image.test_image ... SKIP
datalad_deprecated.metadata.extractors.tests.test_rfc822.test_get_metadata ... SKIP
Failure: SkipTest (Module 'libxmp' failed to load: Exempi library not found.) ... SKIP: Module 'libxmp' failed to load: Exempi library not found.
datalad_deprecated.metadata.tests.test_aggregation.test_publish_aggregated ... SKIP
datalad_deprecated.metadata.tests.test_aggregation.test_aggregate_query ... SKIP
datalad_deprecated.metadata.tests.test_aggregation.test_aggregate_removal ... SKIP
datalad_deprecated.metadata.tests.test_aggregation.test_aggregate_with_unavailable_objects_from_subds ... SKIP
datalad_deprecated.metadata.tests.test_aggregation.test_basic_aggregate ... SKIP
datalad_deprecated.metadata.tests.test_aggregation.test_partial_aggregation ... SKIP
datalad_deprecated.metadata.tests.test_aggregation.test_reaggregate_with_unavailable_objects ... SKIP
datalad_deprecated.metadata.tests.test_aggregation.test_update_strategy ... SKIP
datalad_deprecated.metadata.tests.test_base.test_get_containingds_from_agginfo ... SKIP
datalad_deprecated.metadata.tests.test_base.test_aggregation ... SKIP
datalad_deprecated.metadata.tests.test_base.test_bf2458 ... SKIP
datalad_deprecated.metadata.tests.test_base.test_get_aggregates_fails ... SKIP
datalad_deprecated.metadata.tests.test_base.test_get_metadata_type ... SKIP
datalad_deprecated.metadata.tests.test_base.test_ignore_nondatasets ... SKIP
Failure: SkipTest (Module 'libxmp' failed to load: Exempi library not found.) ... SKIP: Module 'libxmp' failed to load: Exempi library not found.
datalad_deprecated.metadata.tests.test_search.test_listdict2dictlist ... SKIP
datalad_deprecated.metadata.tests.test_search.test_meta2autofield_dict ... SKIP
check that external indexer are called ... SKIP
check that generic indexer is called on external indexer faults ... SKIP
check that generic indexer is called if multiple indexers exist for the same name ... SKIP
datalad_deprecated.metadata.tests.test_search.test_gen4_query_aggregated_metadata ... SKIP
datalad_deprecated.metadata.tests.test_search.test_metadata_source_handling ... SKIP
datalad_deprecated.metadata.tests.test_search.test_search_non_dataset ... SKIP
datalad_deprecated.metadata.tests.test_search.test_search_outside1 ... SKIP
datalad_deprecated.metadata.tests.test_search.test_within_ds_file_search ... SKIP
datalad_deprecated.metadata.tests.test_search.test_search_outside1_install_default_ds ... SKIP
datalad_deprecated.metadata.tests.test_search.test_search_outside1_noninteractive_ui ... SKIP
datalad_deprecated.tests.test__main__.test_main_run_a_script ... ok
datalad_deprecated.tests.test_annexrepo.test_AnnexRepo_add_submodule ... create(ok): . (dataset)

may be because they rely/use on pytest and deprecated still uses nose!!! uff

[github-actions[bot]]

:rocket: PR was released in 0.2.3 :rocket: