Revert "Fix redundant undo entries for earmarks"
This reverts commit 93eaf8d2.
This was supposed to avoid redundant undo/redo entries created when opening the earmarks popover, but it actually disabled undo/redo entirely for earmarks. Oops. Reverting this will unfortunately bring back a bug where undo/redo will sometimes do nothing when you press it. Workaround is to keep pressing undo/redo.
This reverts !42 (merged) so CC @selliott512