Improve shape and texture management

[ForNeVeR]

See TODO[#30] in the code.

I want the texture management to cache the already parsed shapes and maybe textures, in case someone asks for them twice.

We definitely shouldn't read the same shape multiple times for every frame requested.

[Fadoli]

I think it's not really an issue if we cache it in higher level calls, which is most likely what the original game does with the

SHAPECACHE_SIZE 4000000