Updated s3dmesh & created s3dmesh_loader

Started working towards having game entities with meshes. Created a mesh
loader which constructs an s3dmesh using all the necessary elements (eg.
texture_manager, get_blit3d(), etc). Included updated versions of
modules into engine prototype.

We are at the point where working on interconnected modules needs to be
done from engine prototype and not the related module. Soon we will not
want to keep the modules around and only keep the engine prototype.
Merge branch 'master' of https://github.com/Teamwork-2014NBCC/Cheryl