Make UDP remote control mode usable by extending protocol with so-called "cookie" - a token item item which client should insert before each command and which the server will send back verbatim as the first word of reply.
Make UDP remote control mode usable by extending protocol with so-called
"cookie" - a token item item which client should insert before each
command and which the server will send back verbatim as the first word of
reply.

For example, client sends a command to a proxy:

h0h0magic V

Proxy replies with:

h0h0magic 20040302

This is necessary so that clients can match replies to requests even
though UDP doesn't gurantee any particular ordering.

This breaks command protocol backward compatibility, so that
bump protocol version accordingly. Corresponding changes for nathelper will
follow later today or tomorrow.

Sponsored by:	Armin Brunner <abrunner@kom.id.ethz.ch>

kiryu/rtpproxy,synety-jdebp/rtpproxy,synety-jdebp/rtpproxy,mab-netdev/rtpproxy,miconda/rtpproxy,synety-jdebp/rtpproxy,Vocalocity/rtpproxy-pre,viraptor/RTPproxy,viraptor/RTPproxy,gtkiller/rtpproxyd,hongbinz/rtpproxy,sippy/rtpproxy,miconda/rtpproxy,sippy/rtpproxy,Vocalocity/rtpproxy-pre,kiryu/rtpproxy,jevonearth/rtpproxy,miconda/rtpproxy,hongbinz/rtpproxy,mab-netdev/rtpproxy,gtkiller/rtpproxyd,jevonearth/rtpproxy,synety-jdebp/rtpproxy,dsanders11/rtpproxy,jevonearth/rtpproxy,Vocalocity/rtpproxy-pre,DrumTechnologiesLtd/rtpproxy,jevonearth/rtpproxy,kiryu/rtpproxy,DrumTechnologiesLtd/rtpproxy,dsanders11/rtpproxy,hongbinz/rtpproxy,mab-netdev/rtpproxy,hongbinz/rtpproxy,Vocalocity/rtpproxy-pre,sippy/rtpproxy,DrumTechnologiesLtd/rtpproxy,dsanders11/rtpproxy