ui: fixes for dialog text fields (save version dialog + feedback dialog)

[LinqLover]

• disable formatting in text fields (>= Squeak 6.0)
• save version dialog: implement setTextSelector (#message:) correctly to let the view know that the save was successful (will remove the orange triangle)
• save version dialog: fix cancel to actually reset the text (#okToRevertChanges:) (>= Squeak 6.0)
• feedback dialog: instead of hacking #editText:, update all dialog texts prior to submitting via #acceptChanges. This way, undo/redo is working as normally and the edit indication semantics of the toolbuilder are maintained.

Testing plan

Seems to work for my usual interaction patterns with these dialogs. An additional pair of hands would not harm, though. :-) I did not test this in <Squeak 6.0 so far.