Requests for comment/Structured data push notification support for recent changes

Structured data push notification support for recent changes. A long title for a goal that has been named and proposed in various forms. Following is a list of related buzz words:
 * Structured data
 * JSON and/or XML
 * Jabber / XMPP
 * WebSockets (HTML5 / AJAX)
 * PubSubHubbub
 * Push Notification Service

Features

 * Recent changes packages should be easily readable by machine (JSON)
 * Should not be influenced by local wiki modifications (e.g. Interface messages)
 * Should have a way for a client to present a localized sentence describing the sentence (which i18n messages to use, which variables to replace with what)
 * This could probably be done by an API module that returns a map of log type/actions and message-keys. With the new logging framework the order of variables should be more logical as well.