Update dependencies for use of `cl-` functions

[taughz]

Using cl- functions requires Emacs 24.3 and the cl-lib package. Not having this was causing an issue were cl-flet was apparently not working correctly, which was causing error messages like:

buf-move-right: Symbol’s value as variable is void: settings

Fixes #18

[taughz]

BTW, it looks like the last PR caused the issue, because that person added cl- functions/macros, but did not bump the Emacs version and did not include cl-lib. (It could be that this wasn't strictly necessary for early versions of Emacs, but now it is an issue.)