Fix:Ensures that patients won't fall through walls when they die

This commit fixes this issue:
http://code.google.com/p/corsix-th/issues/detail?id=947

It adds code to Die.lua:action_die_start to ensure that patients have enough space to fall over when they die.

It also adds a supporting function to World.lua which checks that a tile has no entity on it and (optionally) isn't in a room: World:isTileEmpty()
Merge pull request #240 from  JASheppard/issue947
I've fixed the faulty Chewbacca fall death animation

The falling part of this animation is faulty with a missing heads layer in frame 30.
So this fix lets the first 21 standing transformation frames be played and then changes the animation to the standard male fall animation by using it as an extra east animation.
This fix also requires the saved game version to be incremented to 83.
Merge pull request #188 from JASheppard/chewbacca_buggy_death_anim_fix
Female patient "flying to heaven" sound fix

The flying to heaven animation for females returned a null sound number (0) for frame 6987 when it should have been returning 123.
Merge pull request #185 from JASheppard/female_goingToHeaven_sound_fix

Female patient "flying to heaven" sound fix