Remove 'undo Stack Window' code from ApplicationWindow

[Russell Taylor]

I noticed a bunch of code relating to variables called undoStackWindow & actionShowUndoStack. I'm pretty sure we don't use these at all in MantidPlot (they're probably a qtiplot relic).

Check and, if I'm correct, remove the code.

[Russell Taylor]

Re #8239. Remove unused undo stack code.

This is inherited code from qtiPlot that was disabled on our side a long time ago. It provided undo functionality on matrices.

Changeset: edc38722f05998beb56507eadc7c4c155e226661

[Russell Taylor]

Re #8329. Remove unused undo/redo action.

This hooked up undo and redo actions to menu items, but these menu items are long-since removed from MantidPlot. The functionality had also gone from Matrices, but is still there via the keyboard shortcuts in Notes (if anyone would ever use it anyway).

Changeset: e87d251d5de55ba8330605484eafb7c0a6684da2

[Russell Taylor]

To test: Code review to see that the code was unused, then check that you see no change in functionality before and after applying the changes. The places to look are at a Matrix (a qtiPlot, not Mantid, one) - where you could already not undo - and a Note - where undo/redo was, and still is, available by keyboard shortcut: (Shift-)Ctrl-Z.

[Martyn Gigg]

Confirmed undo/redo still works for notes and that the code was not used by anything else in MantidPlot.

[Martyn Gigg]

Merge remote-tracking branch 'origin/feature/8239_unused_undo_redo_code_applicationwindow'

Full changeset: ​ee3c1ee0c9f5c8d017c030e4921350592622318d

[Stuart Campbell]

This ticket has been transferred to github issue ​9084