Vega Strike Code

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

Harden BFXM loading against corrupted meshes

Remove redundant VS_PI declaration from unit_xml

Fix upgrade description generation to avoid bogus output with the
"recently" introduced splitting of units.csv, which makes a lot of
missing fields have default values. Detect no-ops (0 for additive) and
defaults, and skip those attributes in the listings.

Fix missiles not always impacting on target due to botched collision
checks. Fix missiles never damaging asteroids due to not checking for
subunits when applying damage. Add debugging output that is useful when
debugging those issues.

Fix querySphere to ignore meshless units that have subunits.
Fixes missiles exploding in your face if you fire them inside an
asteroid field.

Add some more debugging output, and other minor improvements

Optimize handling of subunit-less units by skipping some unneeded work