Fix mis-spelled dependency, and declare dependency on Emacs 24

- "anaphoa" leads to the error reported in https://github.com/milkypostman/melpa/issues/2037
- `lexical-binding: t` implies that the code will only work in Emacs 24+
Merge pull request #34 from purcell/patch-1

Fix mis-spelled dependency, and declare dependency on Emacs 24