[cmyth] LiveTV chain info: returning last program / file handle by recorder
[mythtv-cmyth] Review recordings UID and all about recording events

Many problems with it and myth protocol changes. So to resolve for long term
i rationalized the UID. Now it is formatted like "1002 2013-08-23T14:42:00Z"
and contains myth channel id and recstartts as UTC time. Regardless myth
version our UID use UTC time only.
Depending of protocol command, backend messages could be filled with time
values containing Unix time or string using ISO8601 standard. The string can
contains UTC or local time. To process recording events from backend we must
match backend message with recording UIDs.