Move low-level window width/height functions to C, and high-level functions to Lisp.

Move low-level window width/height functions to C, and high-level functions to Lisp.

* lisp/window.el (window-total-height, window-total-width): Doc fix.
(window-body-size): Move from C.
(window-body-height, window-body-width): Move to C.

* src/window.c (Fwindow_left_column, Fwindow_top_line): Doc fix.
(Fwindow_body_height, Fwindow_body_width): Move from Lisp.  Signal
an error if not a live window.
(Fwindow_total_width, Fwindow_total_height): Move from Lisp.
(Fwindow_total_size, Fwindow_body_size): Move to Lisp.