debug-repl now uses defmacro's new implicit &env arg

[George Jahad]

I've also added an (exit-dr) function that allows you to exit the
debug-repl all the way, if you are nested many levels.

You can get it here:

http://clojars.org/org.clojars.gjahad/debug-repl

(Use the "0.2.0-SNAPSHOT" of the debug-repl if you are not using the
latest Clojure with the new &env arg)

To use it, just add "(use 'alex-and-georges.debug-repl)" to your file,
and insert the "(debug-repl)" command wherever you'd like to see it
pop up.