Level design improvements and bug fixing

I did some minor changes to the level design. Mainly to the last level of the underground area.  The second part was way too easy. You didn't even need the devil guy to complete it. Now it should require bit more of braining to complete.

Also did bunch of bug fixing. The keys and doors were sometimes broken and people just mysteriously disappeared for no reason. There is still at least two annoying bugs on the game that I will hopefully be able to fix soon.