Sort list of Attributes in filter dialog alphabetically

[Flookfinders]

The list of attributes in the filter dialog has no order, so finding a specific attribute means you ahve to read the list carefully rather than quickly scanning the first letter to get to the part of the list you are interested in.

[AgreeDK]

This will be covered in this issue: Hard to find a specific attribute in the list when filtering #449 , so we close this one.