Fix up Linux backend; only use net_udp.c and q_shlinux.c - use sdl2 backend for everything else
Fix incompatible return values for GLimp_Init (qboolean -> int32_t); also include stdint.h
Add #ifdef guards around win32-specific stuff in sys_sdl2.c; Use SDL for clipboard
Add definitions for TRUE, FALSE, and FAR to r_local.h
Remove duplicate definition of r_avertexnormals from r_vlights.c
Add stricmp -> strcasecmp alias for non-win32 platforms
Fix incompatible prototype for ColorLookup
Fix srand in r_warp.c