turned out the whole problem with soft particles what that the vertex
shader used vertex.attrib[8] instead of vertex.texcoord (and with
nvidia drivers those are equivalent)
I integrated the shader source into the c++ code so I don't have to
ship glprogs/soft_particles.vfp
The problem was that negative values (from dhewm3tmpres.xyz) were passed
to POW, and POW doesn't have to support negative bases, according to
ARB_fragment_program.txt, and Intels Linux drive apparently doesn't,
see also https://gitlab.freedesktop.org/mesa/mesa/-/issues/5131
Using MUL_SAT instead of MUL to clamp the value that gets passed to POW
afterwards to [0, 1] fixes the problem without any disadvantages.
so far the code assumed that "result.color" is always used directly,
but the ARB shaders allow creating an alias with the aforementioned
syntax. So turn that into an variable-alias for dhewm3tmpres.
Don't include the lazy precompiled.h everywhere, only what's
required for the compilation unit.
platform.h needs to be included instead to provide all essential
defines and types.
All includes use the relative path to the neo or the game
specific root.
Move all idlib related includes from idlib/Lib.h to precompiled.h.
precompiled.h still exists for the MFC stuff in tools/.
Add some missing header guards.
variable set but not used
Removes some CollisionModel code under _DEBUG which was probably a
leftover, since it was completely useless (its done later anyways).
