Hi! I've 
added arghrad-style sun setup using light entity.
 
 Allows to set most of sun properties using a light entity with "_sun" key set to 1.
 If the light targets an info_null entity, direction towards that entity sets sun direction.
 Light itself is disabled, so it can be placed anywhere in the map.
 
 Following light properties override corresponding worldspawn properties:
 light -> _sunlight;
 mangle -> _sunlight_mangle;
 deviance -> _sunlight_penumbra;
 _color -> _sunlight_color;
 _dirt -> _sunlight_dirt;
 _anglescale -> _anglescale.
 
 Here's a 
compiled version (x86 build, also supports "_falloff" property I've added earlier).