(emacs): Use it everywhere instead of EMACS.
(compile): New target. Compile all Lisp files from scratch.
(recompile): New target. Recompile lisp directory.
(autoloads-with-other-emacs): New target. Build loaddefs.el with
an Emacs executable not built in the current directory tree.
(log-view-mode): Make read-only.
(log-view-current-file): Do final `expand-file-name' in the
current `default-directory'.
(log-view-current-tag): Take an optional `where' arg.
(log-view-diff): New user command.