Groupheadertext doesnt show up on deeper fields

[GEdelmann]

If i define a column like

{name: 'Author', field: 'author.name'}

and group by that column, the row-group-headertext is empty.
Reason: field is not on the root level of the datasctructure (like author.name)

[PaulL1]

This is known and documented in the grouping tutorial. To fix it we need to be able to create fake entities with nested structures, which grouping currently doesn't do.

[PaulL1]

Grouping will still be beta in 3.0, moving to 3.1

[PaulL1]

Fixed a wee while back in the grouping refactor.