Clean up math/

- Remove some unnecessary includes.
- Remove autoconf remnants.
- Split 3dview.* to 3dview.* for t_3dview and 3dtransforms.* for the
  basic 4-vector operations.
- Rename most mat4/vec4 operations to be more descriptive and make some
  3dview operations static, as they were not used outside the source
  file.
- Add some documentation for 3dtransforms.h (but not for all functions,
  so the file itself is not documented).

This removes some legacyheaders/ dependencies from math/, and allows
moving 3dview.* to programs/view/, which is the only user for them.

Change-Id: Ieb51d1d800c07f053eb5a28dfef2a249d5fcfceb