New command image-transform-fit-to-window

New command image-transform-fit-to-window

* lisp/image-mode.el (image-auto-resize, image-transform-resize):
Add new value 'fit-window', meaning to scale the image up or down
to fit the window.  (Bug#)
(image-transform-fit-to-window): New command.
(image-transform-fit-to-height, image-transform-fit-to-width):
Make obsolete in favor of above new command.
(image-mode-map): Bind "s w" to 'image-transform-fit-to-window'.
Move binding for obsolete command 'image-transform-fit-to-width'
to "s i".
(image-mode-map): Add menu entry for
'image-transform-fit-to-window'.  Remove menu entries for above
obsolete commands.
* doc/emacs/files.texi (Image Mode): Update documentation.
(image-transform-fit-both): Doc fix.