Automatically adjust process window sizes

Automatically adjust process window sizes

* lisp/window.el (window-adjust-process-window-size-function): New
customizable variable.
(window-adjust-process-window-size)
(window-adjust-process-window-size-smallest)
(window-adjust-process-window-size-largest)
(window--process-window-list, window--adjust-process-windows):
New functions.
(window-configuration-change-hook): Add
`window--adjust-process-windows'.
* lisp/term.el (term-mode): Observe result of
`window-adjust-process-window-size-function'.
(term-check-size): Delete.