See related SimGear commit e8ffe461
Now the orthophoto texture coordinates are contained in gl_TexCoord[2],
so no need to pass any custom vertex attributes to Effects that use
photoscenery.
- Remove all Compositor Effects and Shaders.
- Unify the low-spec and ALS pipelines in a single pipeline called 'Classic'.
- Readd shadow mapping.
- Move the WS30 Effect and fragment shader out of the Compositor-specific directories.
