[vdr] VDR channel switching notification

[Thomas Sailer <sailer@scs.ch>]

An external application wants to know when vdr is about to
switch channels, and when vdr finished changing channels
(and to what channel). First I wanted to add that functionality
to svdrp, but then found out that vdr only supports one
concurrent svdrp connect :(

I implemented it as a separate unix domain socket, to which
the external app connects and receives channel switch
notification messages. The patch uses a coding style
that is completely different to vdr 8-) Maybe someone
has a better idea how to achieve this functionality.

Tom

http://www.scs.ch/~sailer/vdr-0.99pre5-channelchg-notif.diff