Draft: Allow clicking earmark to hide popup

Adds an option whereby, if you select an earmark, it hides the popup.

For people who tend to fill in earmarks one number at a time (like I do), it's a huge pain to have to click to clear the earmark popup each time after selecting one. If control is held, the popup stays visible.

I also added a small fix so that delete/backspace on a square will actually clear the earmarks if there are any. This is orthogonal, so I could submit a separate merge request for that if preferred.