More UI, more fixes!

I've added a basic error handler screen, so that it's easier for me to receive bug reports. I may make it more verbose if need to, but I think this should do for now.

Also made it so that chunks near a block update update if needed, as not updating them caused blocks near chunk borders to not render their faces, since they need to be updated in order to know that they're no longer being blocked by another tile.

I've added a quick pause screen, as to not confuse people why their mouse isn't locking =)