Fixes and improvements

Fixed endgame messages, added opening instructions.
Changed launch button to spacebar.
Moved and resized some obstacles for improved playability.
Fixed ball velocity/rotation bug on relaunch.
Added sounds for gate opening and enemy hits.
Changed variables:
Time to 5 min
Enemy health to 4 (to show off all textures)
Number of balls to 5
Added a lame title screen

This is just the castle texture with the words "Pinball Quest" on it in
red font. If someone can make a better one in time for the demo, please
go for it.

All you need to do once it's ready is replace the texture on the
TitleScreen in-game object.