Update init-lisp

Updates taken from purcell/emacs.d on Github:
 * Enable auto-compile on load
 * Use compile rather than shell-command for batch byte compilation
 * Bind C-h K to find-function-on-key
Use user-emacs-directory, not ~/.emacs.d
Move .el files into lisp subdirectory

This avoids putting ~/.emacs.d on the load-path, which is apparently
deprecated, and now triggers a warning on start-up in recent Emacs snapshots.