M32Script cleanup. Fixes at least one non-minor and one minor bug.

git-svn-id: http://svn.eduke32.com/eduke32@4798 1a8010ca-5511-0410-912e-c29ae57300e0
m32script: fix tilesizx[]/tilesizy[] access. Can also 'copy' from them.

git-svn-id: http://svn.eduke32.com/eduke32@4799 1a8010ca-5511-0410-912e-c29ae57300e0
voxmodel.c: fix Polymost rendering of voxels.

This reverts/corrects two semantic changes of r4639 as far as what is now
voxmodel.c (formerly part of mdsprite.c) is concerned. One correction ends
up having no effect (m->bscale is always 1.f for voxel models, as far as I
can see), but is the proper rewrite.

Also, in osdcmds.c:registerosdcommands(), tweak two help strings.

git-svn-id: http://svn.eduke32.com/eduke32@4800 1a8010ca-5511-0410-912e-c29ae57300e0