[MNT] Use common CI configuration for add-ons

[janezd]

Issue

Add-ons can now use common configuration for testing.

Description of changes

• I copied the changes from https://github.com/biolab/orange3-survival-analysis/pull/53/files. :)
• I monkey patched get_column into Table if it doesn't exist; this won't affect anybody except other add-ons that might expect it there and do the same as this add-on.
• Reduced the widths of some widgets, disabled tests for size on some others.
• Fixed treatment of nans in one of constructors (third point in #240).

[codecov-commenter]

Codecov Report

:exclamation: No coverage uploaded for pull request base (master@e3fac23). Click here to learn what that means. Patch coverage: 92.50% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #241 +/- ## ========================================= Coverage ? 73.79% ========================================= Files ? 28 Lines ? 4319 Branches ? 583 ========================================= Hits ? 3187 Misses ? 1005 Partials ? 127 ``` | [Impacted Files](https://codecov.io/gh/biolab/orange3-timeseries/pull/241?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab) | Coverage Δ | | |---|---|---| | [orangecontrib/timeseries/aggregate.py](https://codecov.io/gh/biolab/orange3-timeseries/pull/241/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi90aW1lc2VyaWVzL2FnZ3JlZ2F0ZS5weQ==) | `94.47% <ø> (ø)` | | | [orangecontrib/timeseries/\_\_init\_\_.py](https://codecov.io/gh/biolab/orange3-timeseries/pull/241/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi90aW1lc2VyaWVzL19faW5pdF9fLnB5) | `81.81% <75.00%> (ø)` | | | [orangecontrib/timeseries/timeseries.py](https://codecov.io/gh/biolab/orange3-timeseries/pull/241/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi90aW1lc2VyaWVzL3RpbWVzZXJpZXMucHk=) | `90.34% <88.88%> (ø)` | | | [orangecontrib/timeseries/widgets/owdifference.py](https://codecov.io/gh/biolab/orange3-timeseries/pull/241/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi90aW1lc2VyaWVzL3dpZGdldHMvb3dkaWZmZXJlbmNlLnB5) | `100.00% <100.00%> (ø)` | | | [orangecontrib/timeseries/widgets/owlinechart.py](https://codecov.io/gh/biolab/orange3-timeseries/pull/241/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi90aW1lc2VyaWVzL3dpZGdldHMvb3dsaW5lY2hhcnQucHk=) | `75.38% <100.00%> (ø)` | | | [...ngecontrib/timeseries/widgets/owmovingtransform.py](https://codecov.io/gh/biolab/orange3-timeseries/pull/241/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi90aW1lc2VyaWVzL3dpZGdldHMvb3dtb3Zpbmd0cmFuc2Zvcm0ucHk=) | `94.24% <100.00%> (ø)` | | | [...contrib/timeseries/widgets/owseasonaladjustment.py](https://codecov.io/gh/biolab/orange3-timeseries/pull/241/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi90aW1lc2VyaWVzL3dpZGdldHMvb3dzZWFzb25hbGFkanVzdG1lbnQucHk=) | `100.00% <100.00%> (ø)` | | | [orangecontrib/timeseries/widgets/owspiralogram.py](https://codecov.io/gh/biolab/orange3-timeseries/pull/241/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi90aW1lc2VyaWVzL3dpZGdldHMvb3dzcGlyYWxvZ3JhbS5weQ==) | `84.62% <100.00%> (ø)` | | | [...econtrib/timeseries/widgets/owtabletotimeseries.py](https://codecov.io/gh/biolab/orange3-timeseries/pull/241/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi90aW1lc2VyaWVzL3dpZGdldHMvb3d0YWJsZXRvdGltZXNlcmllcy5weQ==) | `92.00% <100.00%> (ø)` | | | [orangecontrib/timeseries/widgets/owtimeslice.py](https://codecov.io/gh/biolab/orange3-timeseries/pull/241/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=biolab#diff-b3JhbmdlY29udHJpYi90aW1lc2VyaWVzL3dpZGdldHMvb3d0aW1lc2xpY2UucHk=) | `73.50% <100.00%> (ø)` | | 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=biolab). 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=biolab)

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