Description:
------------
The current readline implementation does not include support for rl_bind_key. The 
included patch adds the support as follows:
function readline_bind_key_function($key, $callback_func)
where:
$key: Key code to bind to.
$callback_func: A callback function in the form:
function callback($key, $count) where $key and $count are the same parameters 
passed from rl_bind_key()
Setting $callback_func to null will cause the binding to be removed for $key.