Added support for "mapspawn_addon" scripts in addon paths (inspired by L4D2)

sp/src/game/server/vscript_server.cpp

@@ -672,6 +672,8 @@ bool VScriptServerInit()
 				VScriptRunScript( "mapspawn", false );
 
 #ifdef MAPBASE_VSCRIPT
+				RunAddonScripts();
+
 				// Since the world entity spawns before VScript is initted, RunVScripts() is called before the VM has started, so no scripts are run.
 				// This gets around that by calling the same function right after the VM is initted.
 				GetWorldEntity()->RunVScripts();