Squashed commit of the following:
commit c5b72beed4f79675191507a31757b698b6e856d8
Author: vs <vs2009@mail.com>
Date: Sun Nov 21 20:46:05 2021 +1000
Terrain shaders: Fix terrain overlays not rendering correctly with overlays enabled (WS2 terrain shaders, not WS3). Fixes issue 2648: https://sourceforge.net/p/flightgear/codetickets/2648/ . The 1st pass for the overlays technique is a copy of the ALS ultra shaders pass, and it needed an update adding a new uniform.
- 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.
