Add "map" to NSDictionary

If you send the map: message to a dictionary and it will apply the provided
callable to each value and return another dictionary with the results set for
the corresponding keys.

E.g.:

    % (set origin (dict "alpha" 10 "bravo" 20))
    <__NSDictionaryM:7f9224202c50>
    % (set destination (origin map: (do (x y) (+ 1 y))))
    <__NSDictionaryM:7f9224202f40>
    % (destination "bravo")
    21
preparing for a new version: fixed packagemaker path, fixed broken tmbundle repo link
fix typo in README
removed no-longer-needed class extensions from nuke
Fix nubile path to nush
Fix off-by-one indent