(svn r7616) -Cleanup:

-(re)set _rename_[id/what] to -1 to catch invalid calls (main_gui.c)
 -Only invalidate widget of pause/ff instead of whole window (main_gui.c)
 -Remove numbering from WE_ and WC_ as it's not needed, also remove
  non-existing windowclasses (window.h, openttd.h)
 -Give names to some of the enums (window.h)
 -In UninitWindowSystem not only free malloc'd widgets, but also reset the z-array (window.c)
 -Some coding style, comments, etc.

network_client.c

@@ -491,8 +491,7 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_MAP)
 		_network_join_status = NETWORK_JOIN_STATUS_PROCESSING;
 		InvalidateWindow(WC_NETWORK_STATUS_WINDOW, 0);
 
-		// The map is done downloading, load it
-		// Load the map
+		/* The map is done downloading, load it */
 		if (!SafeSaveOrLoad(filename, SL_LOAD, GM_NORMAL)) {
 			DeleteWindowById(WC_NETWORK_STATUS_WINDOW, 0);
 			_switch_mode_errorstr = STR_NETWORK_ERR_SAVEGAMEERROR;