Add preliminary debug facilities to the IDE

The changes here add the preliminary ability to source-map compiled coffeescript lines, and highlight them in the IDE.  It doesn't do anything fancy with that capability yet.
(1) A forked version of CoffeeScript that saves sourcemaps in a global object CoffeeScript.code, is used as the CoffeeScript dependency instead of standard iced CoffeeScript.
(2) The standard mozilla sourcemap library is added as a dependency (it is copied here and added in bower.json).
(3) The IDE adds a new module editor-debug.js that knows how highlight line given by an exception in a subframe: it parses the call stack and highlights the line.