Export the CoffeeScript REPL.

This is done by adding a root level wrapper script for
lib/coffee-script/repl, similar to how the register script is wrapped.
This allows user programs to embed a CoffeeScript REPL without digging
into CoffeeScript's internals.
Fix help for .load
Merge pull request #3460 from datenreisender/correct-repl-help

Fix help for .load
now that github supports renames, coffeescript, not coffee-script
Merge pull request #3448 from leedm777/export-repl

Export the CoffeeScript REPL.
command: deprecate --join
Merge pull request #3477 from davidchambers/deprecate-join

command: deprecate --join