js_of_ocaml update and various new features

* missing c-primitive stubs
* we now hack the runtime completely from ocaml rather than an ugly mix
  of ocaml and javascript
* the only runtime change is to always return dynlink success
* removed kernel.js from repository - I will try to add pre-built
  kernels to releases for windows users

This probably wont work with todays js_of_ocaml checkins, so we'
ll have to update again very soon!

Known issue - camlp4 is printing errors in revised syntax with
the full kernel target!?