Use an as_str method, not Borrow for enum stringification

From IRC:

21:58 < SpaceManiac> Borrow<str> is only appropriate if Hash+Eq+Ord match as well
21:58 < mathstuf> well, these arent Ord or Hash, so i guess AsRef is the way to go then
21:59 < XgF> Borrow<str> is for if your thing is semantically a str :-)
22:00 < Tari> yeah, I wouldn't like either Borrow or AsRef for that
22:00 < Tari> really why you have there is fn(&self) -> &'static str
22:00 < Tari> what you have there, rather
22:01 < mathstuf> make an as_str method then
22:01 < mathstuf> ?
22:01 < XgF> as_str is my usual route for maps to &'static str
22:01 < Tari> as_str or get_name or something
22:01 < mathstuf> k
22:02 < XgF> Borrow<T> is for if you have some heapy-like thing with a slicey-like thing (e.g. Borrow<str> for String)