cherry-pick Albert Gräf's branch: Comment out a bunch of debugging statements which add a lot of noise to the console.

- ret.split(";") should be ret.split(problem_chars[i])
- remove the function from dialog_canvas.html where it isn't needed

send old attrs before new attrs for gatom when clicking "Ok" on the dialog. This way the undo point gets set correctly even if the user has clicked "apply" beforehand

First stab at making the "Cancel" button in gatom dialog actually revert to the previously saved values.