Fixed platform positioning

Platform position was not being initialized correctly
Fixed player collision with platform

Before, the player would teleport to a off-screen location when
colliding with a platform.
Fixed end screen music

Because the yellow music was used in the title screen, the include for
it in the end screen was ignored.
Temporary occlusion culling fix for credits

Due to the way containers handle occlusion culling, most of the credits
never get drawn to the screen. This fixes that, but I'd recommend a more
permanent fix than overriding draw on just this container.
Merge pull request #4 from G33kDude/master

Various bug fixes