* lisp/emacs-lisp/edebug.el: Use lexical-binding.

* lisp/emacs-lisp/edebug.el: Use lexical-binding.
Remove the "edebug-" prefix from non-dynamically-scoped variables.
Mark unused args with underscore.
(edebug-save-restriction, edebug-outside-excursion): Use `declare'.
(edebug-form-data): Use defvar-local.
(edebug-make-before-and-after-form, edebug-make-after-form):
Use backquote.
(edebug-args, edebug-value, edebug-after-index, edebug-arg-mode):
Not dynamically scoped any more.
(edebug--enter-trace): Add arguments `function' and `args'.
Rename from edebug-enter-trace.
(edebug-enter): Call it accordingly.  Bind edebug-function explicitly.
(edebug--update-coverage): Add `after-index' and `value' args.
Rename from edebug-update-coverage.
(edebug-slow-after): Call it accordingly.
(edebug--recursive-edit): Add arg `arg-mode'.  Rename from
edebug-recursive-edit.
(edebug--display): Call it accordingly.  Add args `value',
`offset-index', and `arg-mode'.  Rename from edebug-display.
(edebug-debugger, edebug): Call it accordingly.
(edebug-eval-display-list): Use dolist.