Replace a bunch of weak references with strong ones.

We'll want to re-profile this to figure out where we actually
want weaks. It seems like before we were relying on certain
weaks not being released at the appropriate times, and now
that ARC is doing the releasing for us they're causing some
serious issues.
Drop some not-so-useful CFReleases from ViURLManager.

In fact, they were probably downright dangerous…
Fix ViParser's completeWithError: to not release the command it returns.

I screwed this up while porting. My b.
Fix condition for keyManager:shouldParseKey: check in ViKeyManager.

This was returning in the opposite of the situation it was
supposed to do so in, so keystrokes weren't getting through.