Make it harder to accidentally set print range to '- none -'.

And make the current print range behavior a bit more intuitive.  People
often "remove" ranges to quickly clear any custom ranges if set.  They
wouldn't expect this to actually set the print range to "none".

Also, change the wording of the menu item from "Remove" to "Clear", to
refect this behavior change.

Change-Id: I0369020fedf1c7463d718809875022adef697bf4