Breaks Undo

This plugin breaks the undo stack, as described in this thread: https://forum.sublimetext.com/t/undo-entire-words-instead-of-by-character/11142 (If plugin is enabled, Undo start working by-character and not by-word)

I suspect the guilty line is https://github.com/bobef/ColorSchemeEditor/blob/master/ColorSchemeEditor-ST2.py#L117