Make HildonCheckButton derive from GtkToggleButton

Make HildonCheckButton derive from GtkToggleButton

* hildon/hildon-check-button.h
* hildon/hildon-check-button.c
(hildon_check_button_clicked, hildon_check_button_class_init):
Make HildonCheckButton derive from GtkToggleButton
(hildon_check_button_toggled, hildon_check_button_set_active)
(hildon_check_button_get_active):
Deprecate unnecessary HildonCheckButton API and use the
one from GtkToggleButton instead.

* hildon/hildon-set-password-dialog.c (create_contents)
(hildon_set_password_response_change, hildon_checkbox_toggled)
* examples/hildon-check-button-example.c (button_toggled_cb):
Update to use the GtkToggleButton API

Fixes: MB#4739 (HildonCheckButton should inherit from
GtkToggleButton)

Fixes: NB#132661 (HildonCheckButton should inherit from
GtkToggleButton)