A fix for a tree conflict problem reported by Mark Phippard.
If update/switch caused a tree conflict by trying to delete a modified item, the working copy became unusable. The user couldn't svn add/cp/rm/up/ci at all. And svn resolved didn't help, because it restored the original state that triggered the tree conflict.
This commit changes the update editor so that an incoming delete action will delete a tree conflict victim (and items inside it), instead of skipping the deletion.
Such a victim, or the modified items inside it, can be reinstated via svn add/cp. Or the user can accept the incoming change ("theirs full") via "rm" or "rm -rf".