[gnome-control-center] (6 commits) ...Add an example implementation of a settings panel

[Thomas Wood <thos src gnome org>]

Summary of changes:

  b4fdb6d... Add libgnome-control-center with two new classes: CcShell a (*)
  4ea04c8... shell: add a new settings shell (*)
  799134a... Remove libslab requirement and the internal copy of libslab (*)
  65aea31... Define the extension point name and support variables for p (*)
  a4073bd... shell: initialise the panel extension point (*)
  3748173... Add an example implementation of a settings panel (*)

(*) This commit already existed in another branch; no separate mail sent