Catch horizontal single-stud connections during annotation

The way the annotation interface is currently set up allows users to make one type of connection that doesn't disambiguate between two possible states. For now, the annotation interface should ask for more information if the user has labeled a single-stud horizontal connection, maybe through a dialog box. This information could be passed down to the parser using some keyword argument. Longer-term, we should probably move to annotating the relative translation between connected blocks instead of matching connected studs.