Massive terrain system rewrite.
Added a Native Client port (sound is stereo 44khz only, rendering is gles2, networking is websockets only (sv_port_tcp supports acting as a qw websockets server with non-nacl servers, filesystem is downloads-only - no saves/configs). Blame Zalon. Grr.
git-svn-id: https://svn.code.sf.net/p/fteqw/code/trunk@4013 fc73d0e0-1445-4013-8a0c-d673dee63da5