Move window edge functions to Elisp.

Move window edge functions to Elisp.

* src/window.c (Fwindow_edges, Fwindow_pixel_edges)
(Fwindow_absolute_pixel_edges, Fwindow_inside_edges)
(Fwindow_inside_pixel_edges, Fwindow_inside_absolute_pixel_edges):
Move to window.el.
(calc_absolute_offset): Remove.
* lisp/frame.el (frame-edges): New function.
* lisp/window.el (window-edges, window-pixel-edges)
(window-absolute-pixel-edges): Move here from window.c.
(window-body-edges, window-body-pixel-edges)
(window-absolute-body-pixel-edges): Move here from window.c and
rename "inside" to "body".  Keep old names as aliases.
(window-absolute-pixel-position): New function.