various things

- a couple of README updates
- some color changes for windowcolors
- prevent crash From a bug report, but better than a crash. It
probably renders the map_mode:fit_to_screen ignored in defaults.nh.

win/win32/mhmap.c

@@ -178,6 +178,7 @@ int mswin_map_mode(HWND hWnd, int mode)
 	SIZE mapSize;
 
 	data = (PNHMapWindow)GetWindowLong(hWnd, GWL_USERDATA);
+	if (!data) return mode;
 	if( mode == data->mapMode ) return mode;
 	
 	oldMode = data->mapMode;