Update HzData prototypes.
Small options page fix
Messaging update.

* Add HzMessages for messaging.
** It replaces the deprecated request system by the newer message system.
** Hz.send_X_, different message sending functions, which
  add an action key to the message. Makes the send calls shorter.
** Hz.Messages.receive take a mapping from actions to handler functions.
  For example {showPageAction: function(msg, sender) {...} }
  This receive mapping would be called on messages with the
  'showPageAction' action.

* All uses of requests have been replaced by the HzMessages functions.

* Fix preload from popup. It was broken since the namespace change.