threaded loading code and associated/extensive tweaks.

unified image loading code a little between renderers.
support switching worldmodel in csqc. also associated bugfixes.


git-svn-id: https://svn.code.sf.net/p/fteqw/code/trunk@4758 fc73d0e0-1445-4013-8a0c-d673dee63da5

engine/server/sv_sys_unix.c

@@ -931,6 +931,7 @@ void Sys_DestroyMutex(void *mutex)
 /* Conditional wait calls */
 typedef struct condvar_s
 {
+	//FIXME: these should not be pointers.
 	pthread_mutex_t *mutex;
 	pthread_cond_t *cond;
 } condvar_t;