Enums don't work correctly in table tests

[S1artie]

No description provided.

[S1artie]

The general issue of tabletests not being able to work with enums at all has been fixed - enums can now be used as parameters and default results in tabletests. However, there are still some (possibly) open issues which are more complex and thus were postponed:

• It has not yet been checked whether enum values as named results work correctly (theoretically they should, but...)
• Enum values are not being suggested correctly by the autocompletion in some situations.

I'll keep this issue open until all those problems have been addressed.

[S1artie]

I consider this issue closed now. The autocompletion task, due to it being pretty tricky and time-consuming and, well, not that critical - has been splitted off into an own issue: #53