Add and rewrite window size functions in window.el.

Add and rewrite window size functions in window.el.

* window.el (window-safe-min-height, window-safe-min-width):
New constants.
(window-size-ignore, window-min-size, window-min-size-1)
(window-sizable, window-sizable-p, window-size-fixed-1)
(window-size-fixed-p, window-min-delta-1, window-min-delta)
(window-max-delta-1, window-max-delta, window-resizable)
(window-resizable-p, window-total-height, window-total-width)
(window-body-width): New functions.
(window-full-height-p, window-full-width-p): Rewrite using
window-total-size.
(window-body-height): Rewrite using window-body-size.