Rename the asset programs to shaders

[BenjamenMeyer]

The programs folder in the assets is really the OpenGL Shaders. We should rename the directory to be apparent about what it contains.

Revealed by #29 where the programs were missing from the tarballs.

[stephengtuggy]

The programs folder contains two types of GLSL-language programs, I believe: fragment programs and vertex programs. I think the shaders have their own folder.

We could, perhaps, look at splitting the fragment programs and vertex programs into separate folders. Not sure if this is something we want to do or not.

[BenjamenMeyer]

@stephengtuggy we should give it better clarity - that's really what this issue is about; even if we do a structure like opengl/shaders, opengl/fragments, opengl/vertex, etc.

[stephengtuggy]

@stephengtuggy we should give it better clarity - that's really what this issue is about; even if we do a structure like opengl/shaders, opengl/fragments, opengl/vertex, etc.

Makes sense.