change regex to end on Ctrl-Z (i.e. \x1A), exclude from param matching group

As far as I can tell, the "parameter" portion of a message can validly include spaces (e.g. a "NAT", "QSTN" should return the currently playing artist from USB/NET, which can include spaces, e.g. "ISCP!1NATPink Floyd"). The old regex would return only "Pink" as the parameter returned from the Onkyo device. 

And obviously, [Pink](http://en.wikipedia.org/wiki/Pink_(singer)) and [Pink Floyd](http://en.wikipedia.org/wiki/Pink_Floyd) are quite different. :)

As far as I can tell, messages actually end in \x1A. This change terminates the parameter group when it encounters that character. 

Great stuff, by the way, Mike! I appreciate your effort in building this. I'm building a higher level library (e.g. stuff like `instance.stop`; `instance.station = "93.9"`) using this library. If you're amenable, I may send you more pull requests as I work on it.