This patch removes the internal system menu from WindowServer and
replaces it with two IPC API's:
SetSystemMenu(menu_id)
SetSystemTheme(theme_path, theme_name)
These API's will allow us to complete the SystemMenu program and
move it entirely out of process.
Move applet logic to the own class. Remove applet code from MenuManager.
With new AppletManager applet order is configurable via WindowManager.ini file.