[UNSTABLE] Cache/Resource-Optimization Update (Part One)

This update introduces a new splashscreen, and resource caching. All the
images, sounds, fonts, etc will be loaded upon startup, and "cached"
into a Resource handler (ResourceCache).

This should improve level loading times, and any odd stutters when
loading particles (which did occur and was very noticeable when it gave
off 500ms of update lag).

Several other things were also introduced, but I don't really remember
all of them. One being skid dust particle effect for mario's turn-around
skid.

Side note: things were disabled, such as where some fonts were being
used, due to the resource handler not being fully implemented yet. This
will be the next big update, as a lot of the world/main
game/UI/player/enemy/tile class files will need to be updated to
accommodate the new physics engine, and better scene loading.