adds ability to undo until the page is cleared
fixes bug where undo button would not refresh view until mousemove
adds ability to undo until the page is cleared
fixes bug where undo button would not refresh view until mousemove
updates layers in undo method to 0 index
resolves merge conflicts
Merge pull request #26 from vertigokidd/clean_slate

Adds ability to undo until page is cleared and fixes bug where undo button would not refresh view until mousemove