STL File Reader

In addition to the STLREAD import function, this submission also includes a small demo that loads an STL model of a human femur bone.

FV = STLREAD(FILENAME) imports triangular faces from the binary STL file
indicated by FILENAME, and returns the patch struct FV, with fields 'faces'
and 'vertices'.

[F,V] = STLREAD(FILENAME) returns the faces F and vertices V separately.

[F,V,N] = STLREAD(FILENAME) also returns the face normal vectors.

The faces and vertices are arranged in the format used by the PATCH plot
object.