Fixed rotate_server_screen.

The ServerScreen option in LCDd.conf and the -i command line parameter were parsed in server/main.c, but the value of rotate_server_screen was not respected in server/serverscreens.[c,h].

server/serverscreens.h

@@ -16,6 +16,8 @@
 
 extern Screen * server_screen;
 
+extern int rotate_server_screen;
+
 int server_screen_init ();
 int server_screen_shutdown ();
 int update_server_screen ();