New features:
* Introduce `js2-minor-mode', to run parser with another major mode active.
* Add `js2-display-error-list'.
Breaking changes:
* Emacs 24 only.
* Don't set up mode association automatically for *.js files.
* Get rid of the mirror-mode (use electric-pair-mode).
* Get rid of the auto-indent code (use electric-indent-mode).
* Get rid of the js2-rebind-eol-bol-keys.
* Don't rebind RET. Use M-j to extend comments.
* Don't bind `js2-mark-defun' and `js2-narrow-to-defun'.
Other changes:
* Derive from `prog-mode'.
* Improve documentation style.
* Consistently use 'js2-' prefix.
* Replace `defsubst' with `defun' is many cases.
* Don't use `save-match-data' unless required (which is currently never).