initial commit
added undo and redo buttons, extended UndoTree class with forward() and revert() methods
added View menu which contains an entry to hide and show the Traceback view, which is now hidden when executing code and some other stuff.
implemented saving and loading of files
Merge branch 'master' of github.com:nr-plugins/nr-c4dprototyping

Conflicts:
	.gitignore
traceback list only displayed if traceback is available