Make compatible with Python 3
Fix ray-aabb intersection code and test
Merge branch 'fix-ray-aabb-intersection' of git://github.com/jstasiak/Pyrr
Make AABB tests match other test format.

Move individual tests into sub functions.
Fix divide by zero warning in ray_intersect_aabb.

Avoid divide by zero warnings by using infinity if
the divide value is 0.0.
Rename identity to create_identity.

This is in keeping with the coding standard.
Remove to_matrix33. Use matrix33.create_from_matrix44.
Minor syntax changes.

Ensure header comment is """ not '''.
Ensure imports come after header.
Remove @author and creation date comments.
Fix 3x3 rotation matrix generation + clean up a bit
Fix import error triggered by missing import.

Apparently decorators cause mega explosions in
the module loader if the decorator itself hasn't
been imported!
Update methods that used identity.

identity is now create_identity.
Rename identity to create_identity.
Rename identity to create_identity.
Update tests to latest method names.
Fix documentation string issue in generate_normals.

Also improve the examples.
Fix order of parameters in some functions.

If function is a_intersect_b, then parameters
should be a, b. Not b, a.
Further rename methods and reorder parameters.

Ensure functions are type_check_type or type_check.
Rename closest_point_on_ray to point_closest_point_to_ray.
Rename closest_point_on_line to point_closest_point_to_line.
Rename closest_point_on_line_segment to point_closest_point_on_line_segment.
Rename are_rays_parallel to rays_are_parallel.
Rename are_rays_coincident to rays_are_coincident.
Rename height_above_plane to point_height_above_plane.
Rename closest_point_on_plane to point_closest_point_on_plane.
Rename does_sphere_intersect_sphere to sphere_does_intersect_sphere.
Rename closest_point_to to closest_point_on.
Rename and correct ray checks.

Rename rays_are_parallel to ray_parallel_ray.
Rename rays_are_coincident to ray_coincident_ray.
Fix ray_coincident_ray not handling non-normalised
direction vectors.
Added a comment regarding ray_coincident_ray and how
it differs from ray_parallel_ray.
Add vector_parallel_vector.

Change ray_parallel_ray to use vector_parallel_vector.