Port over the various extensive test files

[holtgrewe]

asssembly mapper

• [x] test_hgvs_variantmapper_near_discrepancies.py

variant mapper

• [x] test_variantmapper_cp_real.py
• [x] test_variantmapper_cp_sanity.py
• [x] test_variantmapper_gcp.py
• [ ] test_clinvar.py
• [ ] test_grammar_full.py

[holtgrewe]

Postponing test_grammar_full.py to #30.

[holtgrewe]

The clinvar test case has issues in upstream as well:

• https://github.com/biocommons/hgvs/issues/380