Rework the injected script:

Rework the injected script:

* Make it object-based
* Functions now take hashes (like jQuery) instead of parameter lists
* There is now a single response dispatcher instead of writing one
  per GSS method call
* Implement the gss_error C-macro as a JavaScript function
* Split the callback into two callbacks: success and error.
* Add checking for whether the message returned from the C code has a
  matching nonce/method tuple.