* lisp/comint.el: Use lexical-binding. Use std completion UI. Require CL.

* lisp/comint.el: Use lexical-binding.  Use std completion UI.  Require CL.
(comint-dynamic-complete-functions): Use comint-filename-completion.
(comint-completion-addsuffix): Tweak custom type.
(comint-filename-completion, comint--common-suffix)
(comint--common-quoted-suffix, comint--table-subvert)
(comint--complete-file-name-data): New functions.
(comint-dynamic-complete-as-filename, comint-dynamic-complete-filename)
(comint-dynamic-list-filename-completions): Use them.
(comint-dynamic-simple-complete): Make obsolete.
* lisp/minibuffer.el (completion-in-region-mode):
Keep completion-in-region-mode--predicate global.
(completion-in-region--postch):
Assume completion-in-region-mode--predicate is not null.