[WIP] [FIX] OWMergeData removes table meta attributes

[AndrejaKovacic]

Issue

Fixes #3289

Description of changes

I added an optional parameter in table.py, method from_numpy can now accept data_attributes.

Includes

• Code changes
• Tests
• Documentation

[CLAassistant]

All committers have signed the CLA.

[janezd]

Could you also add the argument data_attributes to Table.from_list, for the sake of consistency? Alternatively, you can remove the argument from from_numpy and just attach attributes in the widget (instead of passing them as an argument), that is, without modifying Orange.data.table. I have no preference.

Please remove the unwanted unrelated change in application.py. :)

Also, please squash the commits into a single one.

[lanzagar]

Well, in addition to from_list there are from_domain, from_table, from_table_rows above and none have this parameter. So my preference is to leave the Table API unchanged and fix the widget instead.
And looking at how the tables are merged, I would say copying the attributes is not the only thing missing. At least the fact that ids are not retained is also a problem. Using from_numpy has been problematic in other cases (many of them now fixed) and is not a good choice here as well. Appending columns from extra_data to some primary data set should probably retain as much as possible from the main dataset (including ids and attributes).

[AndrejaKovacic]

Replaced by #3474.