Allow displaying tool bar on the bottom of the frame

Allow displaying tool bar on the bottom of the frame

* src/xterm.c (x_clear_under_internal_border): Subtract bottom
margins before clearing bottom border.
(XTflash): Subtract bottom margins before flashing mini window.

* src/xfns.c (x_set_tool_bar_position): Allow setting different
values outside of GTK+.
(frame_geometry): Adjust inner width and height for tool bars
placed on the bottom.

* src/xdisp.c (init_xdisp): Calculate using top margins only.

* src/window.c (resize_frame_windows): Fix commentary.

* src/w32fns.c (Fw32_frame_geometry): Report tool bar position
correctly.
(w32_clear_under_internal_border): Subtract bottom margins
prior to clearing bottom border.
(w32_set_tool_bar_position): New function.
(Fw32_frame_edges): Subtract bottom tool bar from inner width and
height.
(w32_frame_parm_handlers): Add `set_tool_bar_position' parameter
handler.

* src/pgtkterm.c (pgtk_flash): Subtract bottom
margins before clearing bottom border.
(XTflash): Subtract bottom margins before flashing mini window.

* src/pgtkfns.c (frame_geometry): Set `inner_top' correctly.
(Fpgtk_set_mouse_absolute_pixel_position):
(Fpgtk_mouse_absolute_pixel_position):
(Fpgtk_page_setup_dialog):
(Fpgtk_get_page_setup): Wrap lines which cause C Mode to hang.

* src/nsterm.m (ns_clear_under_internal_border): Subtract bottom
margins before clearing bottom border.

* src/nsfns.m (ns_set_tool_bar_position): New function.  Error if
arg is not top.
(ns_frame_parm_handlers): Add that as the handler for
`tool-bar-position', to prevent it from being set to an invalid
value.

* src/haikuterm.c (haiku_flash): Subtract bottom margins before
flashing mini window.
(haiku_clear_under_internal_border): Subtract bottom margins
before clearing bottom border.

* src/haikufns.c (haiku_set_tool_bar_position): Allow setting
values other than `top'.
(frame_geometry): Take bottom margin into account when calculating
inner dimensions.

* src/frame.h (struct frame): Always define `tool_bar_position'.
(fset_tool_bar_position): Define function everywhere.
(FRAME_TOOL_BAR_POSITION): Define correctly on all toolkits.
(FRAME_TOOL_BAR_TOP_HEIGHT):
(FRAME_TOOL_BAR_TOP_LINES):
(FRAME_TOOL_BAR_BOTTOM_HEIGHT):
(FRAME_TOOL_BAR_BOTTOM_LINES): New macros.  Each pair returns the
tool bar dimensions only if the tool bar position is set
appropriately.
(FRAME_TOP_MARGIN, FRAME_TOP_MARGIN_HEIGHT): Only add tool bar
height if it is placed at the top of the frame.
(FRAME_BOTTOM_MARGIN, FRAME_BOTTOM_MARGIN_HEIGHT): Add ``bottom
margins''.
(FRAME_MARGINS, FRAME_MARGIN_HEIGHT): Move original margin macro
here.
(FRAME_PIXEL_HEIGHT_TO_TEXT_LINES):
(FRAME_TEXT_TO_PIXEL_HEIGHT):
(FRAME_PIXEL_TO_TEXT_HEIGHT):
(FRAME_INNER_HEIGHT): Subtract both vertical margins.

* src/frame.c (adjust_frame_size): Subtract both top and bottom
margins to determine the inner height.
(make_frame): Initialize `f->tool_bar_position' unconditionally.

* src/dispnew.c (adjust_frame_glyphs_for_window_redisplay): Place
internal tool bar on bottom if requested.

* doc/lispref/frames.texi (Frame Layout): Describe the possibility
of the tool bar being placed below the inner area of the frame.
(Layout Parameters): Describe that `tool-bar-position' is now
supported almost everywhere.