Big changes in code of clients, screens and widgets.

- Moved and altered code to create, destroy and manipulate clients, screens
  and widgets in an OO-like manner.
- Moved command execution code to a commands directory, splitting commands to
  what subject they are concerned.
- Menus are temporary disabled while working on new menu structure.

server/serverscreens.h

@@ -14,7 +14,7 @@
 
 #include "screen.h"
 
-extern screen *server_screen;
+extern Screen * server_screen;
 
 int server_screen_init ();
 int update_server_screen (int timer);