Add client/javascript.js to .gitignore
Change tests not to rely on ILazySeq
Kill toArray
Kill ILazy.forcingMethods
Kill ILazy.lazyMethods

All methods on ILazy are now deferred.
Kill ILazySeq
Incrementally render ILazies to JSON

Previously, rendering to JSON would force ILazies, and only yield the JSON
once forcing completed.  In order to display progress, we need to
be able to return JSON incrementally as ILazy forcing completes.

This commit adds the necessary support to the interpreter, but does not
update the client protocol and client: The server still waits for
JSON rendering to finish before sending it to the client.  But it does
it outside of the interpreter.
Remove call/cc

It had some bugs, and planned interpreter changes mean we're going to
drop it anyway.
Force arguments to builtins
More accurate names for grammar and generated parsers