Quaternion math routines

Quaternions are an alternate way to represent the rotation part of a transformation, and can be easier to manipulate than matrices. As with a matrix, you can encode a geometric transformations in one, concatenate several of them to merge multiple transformations, and apply them to a vector, but they can only store pure rotations. The big advantage is that you can accurately interpolate between two quaternions to get a part-way rotation, avoiding the gimbal problems of the more conventional euler angle interpolation.

Quaternions only have floating point versions, without any _f suffix. Other than that, most of the quaternion functions correspond with a matrix function that performs a similar operation.

Quaternion means 'of four parts', and that's exactly what it is. Here is the structure:
   typedef struct QUAT
      float w, x, y, z;
You will have lots of fun figuring out what these numbers actually mean, but that is beyond the scope of this documentation. Quaternions do work -- trust me.