Add 1025x1025 version of testing heightmap

Signed-off-by: Paul Holden <paulholden2@gmail.com>
Re-work heightmap processing and generation

- Use pointers to arrays instead of to a heightmap object. Work on
  properties of heightmaps instead of a heightmap object itself. Will make
  it easier to run tests on the individual functions of the heightmap
  implementation.

Signed-off-by: Paul Holden <paulholden2@gmail.com>
Merge branch 'hmap-changes'

Signed-off-by: Paul Holden <paulholden2@gmail.com>