Datainput control for Text element doesn't work correctly with undo/redo stack

There are at least two issues with datainput controls linked to text elements:

• Any change creates two undo points, first of which doesn't seem to do anything
• Redoing control change doesn't update visual status.

Slide and timeline controls seem to work fine (at least with the pending fix to QT3DS-1074, which adjusts their transaction logic to fix a wider issue with undo/redo stack).