Use gio trashing directly, and get rid of the confirmation dialog
Slightly improve the VC delete error dialog, introducing a new helper
Make the error helper import and use the toplevel window by default
Rework more run_dialog usage
Remove dialog use from CVS in favour of logging

These were low-level errors that indicated broken things in the CVS
repository, not general problems in Meld. There's little point in
displaying such errors to the user, so logging is more appropriate.
Remove cvs module from POTFILES, since all strings are gone from there
More error dialog usage in dirdiff
Use gio trashing in dirdiff as well
Move shelljoin from misc to vc and simplify
Move installation check into VC modules
vcview: VC Choosing minor refactoring
vc.git: Move status regex to class level
vc: Move repository root finding to class and adjust subclasses

The way Meld has previously dealt with figuring out whether a path is
a valid repository is to try to create the Vc, and then catch the
resulting explosion if it fails. While this works, it ends up having
some very weird side effects in VcView, and makes for some overly
complicated logic when figuring out what VC to use.
vc: Clean up valid_repo calls
vc: Move validity checks to class methods; use classes in VcView
vcview: Move most of combobox creation into glade
vcview: Minor refactor
vc: Move hack for adding from parents into individual VCs

CVS and older SVN require directories to be added from their direct
parents. This was dealt with via a hack in VcView. This commit moves
the hack into the CVS and SVN modules, and adds an accompanying
new-style API call for adding files.
vcview: Move actions into UI file
Add HistoryCombo to the glade catalog