The only compatibility mode feature left is the main drawer function using glBegin/glEnd but changing that is not as urgent as the rest.
This also cleans up the fog application and adds the exponential fog mode again that somehow got lost over time.
The builtin matrices are no longer available in modern GLSL, preventing an upgrade of the shader.
Also perform better reporting of shader compilation errors.
This is one unbelievable piece of weird coding based on the 15 year old concept to avoid conditionals at all costs.
As a result the code is totally unreadable and no longer really portable to modern OpenGL.
This has to be done in small pieces.
Currently this only contains the main Polymost shaders and the resources from nblood.pk3.
The latter cannot be used yet because the Build resource management system is too stubborn to add the newly added file without some changes.
It's better to refactor the entire system instead.
