commands that need a lock should prompt to steal it

If a bzrdir component is locked, bzr currently advises you to run break-lock.

Irene reports some trouble from her users in discovering how to use this. It might be nicer if bzr asked you if you wanted to break/steal the lock, as is done by emacs and vim. There is a special but common case that the holding process was owned by you and running on the same machine. There is enough information in the lock info file to identify this. In that case we can quite reliably tell(*) if the process is still running or not, and we can show that information too.