Re-implement childframe with emacsgtkfixed

Re-implement childframe with emacsgtkfixed

* src/emacsgtkfixed.c (G_DEFINE_TYPE): Make emacs_fixed_get_type public.
* src/emacsgtkfixed.h (EMACS_TYPE_FIXED): Make emacs_fixed_get_type public.
* src/gtkutil.c (xg_frame_set_char_size): Call appropriate functions
by whether the frame is a child frame or not.
(xg_create_frame_widgets): Use GTK_WINDOW_TOPLEVEL when creating child frame.
(xg_create_frame_outer_widgets): New function.
(xg_set_skip_taskbar): Call only when top-level frame.
(xg_set_no_accept_focus): See appropriate widget.
* src/gtkutil.h: New declaration.
* src/pgtkfns.c (pgtk_set_name_internal): Do only when top-level frame.
(Fx_create_frame): Reparent the frame.
(frame_geometry): Call appropriate functions
(syms_of_pgtkfns): Port from X code.
* src/pgtkterm.c (x_free_frame_resources): Destroy appropriate widget.
(x_calc_absolute_position): Port from X code.
(x_set_offset): Re-port from X code.
(pgtk_set_window_size): Use appropriate widget.
(pgtk_make_frame_visible): Use appropriate widget.
(pgtk_make_frame_invisible): Use appropriate widget.
(x_set_parent_frame): Reparent the frame.
(x_set_z_group): Process only when top-level frame.
(pgtk_text_icon): Process only when top-level frame.
(set_fullscreen_state): Process only when top-level frame.
(frame_highlight): Hold ref.
(frame_unhighlight): Hold ref.
(pgtk_window_is_of_frame_recursive): Prune child frames.
(pgtk_window_is_of_frame): Prune child frames.
(print_widget_tree_recursive): Don't call this when not debugging.
(pgtk_handle_draw): Don't call this when not debugging.
(pgtk_set_event_handler): expect map-event for edit_widget not outer widget.
* src/pgtkterm.h (FRAME_WIDGET): New macro.