model: Implement the lapped texture mapping method
mode: avoid allocating temporary vertices on the heap

This updates the rut-model code rely on stack allocated Vertex
structures to hold intermediate results when generated patched
meshes. This updates the various calculate_ functions to take a pointer
to a vertex for storing the result instead of having those functions
allocate a new vertex via g_new
hair: Improved hair implementation using fins

Implemented a particle engine for the hair so it appears "messy". Added
fin geometry and texture generation to decrease the aliasing around the
mesh silhouette. Applied gaussian blur to each hair strand for realistic
hair coloring. Made use of the patched texture capabilities to ensure
shell textures don't stretch.

NOTE: This patch forces all models to default to lapped texture mapping.
Furthermore fins are only supported for imported models, not built-in
geometry.