Add bindings for fab vagrant venv_shell
Configure regexp builder

Normally, the regexp builder helps you build regexpses that can be used in lisp code. This setting, reb-re-syntax, uses the syntax for building strings when interactively calling functions. My most common use case is the replace-regexp function, so this is useful.
Make smex behavior consistent

Strangely, <menu> is an alias for M-x, but not for smex when smex is mapped to M-x.