Add the no texture shaders.
Shaders that use texture coordinates fail when no texture is used.

* The use/removeTexture functions now reload the underlying shader
  in order to use the shader version using (or not) texture coordinates
Forgot to commit the no texture shaders.
v0.5.1: Fix a bug with the shaders when not using textures.
Adding compatibility with textures for the shaders broke them when not
using textures. This is now fixed.

The shader is reloaded each time useTexture or removeTexture are called.

Merge branch 'develop'