First pass at porting closure.clj and cljsc.clj.

Build like this:
    ../bin/cljsc ../src/cljs/cljsc.cljs > cljsc.js && cp ../src/cljs/goog.js out

Run like this:
    ./run.js cljsc.js hello.cljs > hello.js

It will attempt to compile using out2 as the output directory
and will blow up trying to compile core.cljs.