Rearrange renderer shutdown process
Fix various "random" texture glitches
Default image extension to empty string
Connection screen isn't modal
More fixes to textures loading
Oops
* Don't load binary GLSL progs from seemingly broken glsl.cache.bin

Also default gl_ext_get_program_binary to 0: too many random glitches on AMD hardware :(
Fix inaudible sounds in snd_qf
Don't use implementation-dependent PolygonOffset
Wait for the thread to complete context setup before issuing any more GL cmds
Merge branch 'master' of github.com:viciious/qfusion
Initial part of ETC1 support: decompression code