Vega Strike Code

GCC 7 fix: use const char* instead of char*

GCC 7 is far stricter with casting from/to const,
so use const char * in vssetup structures and
functions to avoid having to cast constant strings
into mutable char*

GCC 7 fix: cannot return a char, must use char*

Fix member access through pointer (GCC7 fix)

Remove useless import

Fix rlaan-cockpit normals, add indirect glow

Fix light_cockpit normals, improve indirect glow

Rework objconv to rely less on runningbytenum, which is error prone:
measure section sizes instead with ftell. Fix signed-unsigned mismatch
that was causing corruption.

Mesher: warn when a material is missing from the .mtl file

Fix 3D cockpit rendering:
- Z-buffer range was off such that the whole cockpit was clipped
- Lighting was wrong, since the camera was centered but ligths weren't
adjusted for it
- Disabling Z culling hasn't been working since shader techniques were
introduced, that force their own culling modes, so remove the option
- Transform matrix was flipping the X axis and thus flipping face
normals, fix it to be consistent with GFXLookAt

Avoid redundant Z-clear when some stages are empty, honor nocamerasetup flag