* lisp/emulation/viper(-cmd)?.el: Use lexical-binding.

* lisp/emulation/viper(-cmd)?.el: Use lexical-binding.

* lisp/emulation/viper-cmd.el: Use lexical-binding.
(viper-change-state-to-vi, viper-change-state-to-emacs): Allow dummy
args, for use in advice-add.
(viper--init-message): Rename from init-message.
(viper-minibuffer-standard-hook): Adjust accordingly.
(viper-undo): Remove unused var `modified'.
(viper-read-string-with-history, viper-set-searchstyle-toggling-macros):
Don't use dynamic vars as args.
(viper-submit-report): Clarify use of dynamic vars.

* lisp/emulation/viper.el: Use lexical-binding and nadvice.
Remove redundant :group keywords.  Group the (if viper-mode) at top-level.
Use add-function rather than a `(lambda ...).
(viper--advice-list): New var.
(viper--advice-add, viper--deactivate-advice-list): New funs.
(viper-go-away, viper-set-hooks, viper-non-hook-settings): Use them.
(viper-non-hook-settings): Don't hook into find-file any more.