pxlTextGenerator; Add undo / redo function

[ProcStack]

pxlTextGenerator

Add in an Undo and Redo feature

ToDo-
TextBase Viewer - Store prior ReachPixel / Add / Remove / Edge pixel arrays
Character Settings - Store prior changes to an array, [parameter, value]
Page Output - Store prior changes to an array, [parameter, value]
Page Output - Add undo button to deleting a Page Group. (Object still exists, just not displayed)