demo menu now properly lists the contents of archives.
demos played from subdirs/archives can now chain properly.
autodetect nehahra's demos. Add -nehahra argument to register/override cvar defaults (and set the right gamedir+startmap).
fix some q2 download bugs.
lame attempt at proper sRGB support (gl+vk+d3d9+d3d11 renderers).
fix q3bsp wrong-lightmaps bug.
match DP's viewzoom behaviour by not applying it when VF_[A]FOV was explicitly used.
fix d3d9 issue with missing textures screwing up blend modes.
vk: use a staging buffer instead of a staging textures per mip.
git-svn-id: https://svn.code.sf.net/p/fteqw/code/trunk@5128 fc73d0e0-1445-4013-8a0c-d673dee63da5