Completer::complete takes a mutable reference.
Editor takes a Option<Rc<RefCell<Completer>>.

Breaking change: by default, iterator does not add automatically
to history anymore.

Alternative to PR #120

Add Cargo category and badges

Add ability to get constant reference to history from Editor

Don't preserve history on the gh-pages branch when pushing latest documentation

Vi mode (#94)

Function key
Control + arrow keys
Shift + arrow keys
Insert key

Not tested on windows