Import and rebase Max NewGRFs patch

Fix trailing whitespace, clean up code a bit

http://www.tt-forums.net/viewtopic.php?p=894743#p894743

src/network/network_gui.cpp

@@ -31,6 +31,8 @@
 #include "../core/geometry_func.hpp"
 #include "../genworld.h"
 #include "../map_type.h"
+#include "../newgrf.h"
+#include "../error.h"
 
 #include "../widgets/network_widget.h"
 
@@ -1177,6 +1179,10 @@ struct NetworkStartServerWindow : public Window {
 			}
 
 			case WID_NSS_GENERATE_GAME: // Start game
+				if (CountSelectedGRFs (_grfconfig_newgame) >= MAX_FILE_SLOTS_IN_NETWORK) {
+					ShowErrorMessage(STR_NEWGRF_ERROR_TOO_MANY_NEWGRFS_LOADED, INVALID_STRING_ID, WL_ERROR);
+					break;
+				}
 				_is_network_server = true;
 				if (_ctrl_pressed) {
 					StartNewGameWithoutGUI(GENERATE_NEW_SEED);