Re-organize API.

EekGtkKeyboard is now a subclass of GtkWidget not EekKeyboard.  Widget
creation is done as follows:

layout = eek_xkl_layout_new (...);
keyboard = eek_keyboard_new (layout, 640, 480);
widget = eek_gtk_keyboard_new (keyboard);

Broken Clutter support is temporarily disabled.

eek/eek-section.h

@@ -107,9 +107,6 @@ EekKey *eek_section_create_key           (EekSection     *section,
 
 EekKey *eek_section_find_key_by_keycode  (EekSection     *section,
                                           guint           keycode);
-EekKey *eek_section_find_key_by_position (EekSection     *section,
-                                          gdouble         x,
-                                          gdouble         y);
 
 G_END_DECLS
 #endif  /* EEK_SECTION_H */