Add support for CVS branches/tags/"release" arguments in general

There ought to be some way to specify release numbers or tags for the checkout when setting up a project from CVS via New File Or Project->Import Project->CVS Checkout. This would typically be used to work on branches, but the functionality might not need to know about that.

Also, it would be nice if there could be some kind of information about the release numbers/tags in the project list - for the case where you have checked out different branches simultaneously.