soy.scenes.Landscape

[ArcRiley]

Create a new soy.scenes class akin to #928 but which is a heightmap instead of a plane.

A single-channel texture should provide a heightmap with a single material. Later 2, 3, and 4 channel textures will allow for other functionality such as per-vertex material selection.

Finish with an example of a simple heightmapped scene in action.

[ArcRiley]

http://opende.sourceforge.net/mediawiki-1.6.10/index.php/DHeightfield will be useful for reference.

[JonNeal]

Reopened because this entire class needs rewriting. Horrible efficiency and the code looks terrible.