[ptp-dev] protocol change

[Greg Watson <g.watson@xxxxxxxxxxxx>]

Hi,

I've made a minor change to the proxy protocol. The proxy must now  
send a SHUTDOWN event in response to a QUIT command, rather than an  
OK event. I've added the appropriate helper functions to the proxy  
library.

This is needed to add future support for multiple channels to a  
single proxy connection.

I have updated the wiki documentation appropriately.

Greg