Updated IRP for uSCXML

Hey there,

attached is the updated IRP for uSCXML, we now pass all tests but:

- the one where the XPath DM is hardcoded
- test513 which tests for an unimplemented http extension
- test520 "this is some content” is unescaped in search string
- test531 <content>_scxmleventname=test</content> is invalid to set the event name in our implementation
- test579 with the recent addition of history transitions