[pvr.tvh] initialize m_seekTime in constructor

Also added a constant to indicate an invalid value
[pvr.tvh] initialize all fields in SEvent
[pvr.tvh] store the channel while looping for deleted schedules and events

the iterator may be invalid by the time TriggerEpgUpdate is called
[pvr.tvh] drop logically dead code (NULL check was done earlier)
[pvr.tvh] drop support for Openelec 3.2
[pvr.tvh] - put general message processing in thread

This is to ensure that demux data get's processed efficiently. In reality I
could (should?) also split out the less critical demux status messages. But
I think at this stage that's probably not necessary.
[pvr.tvh] - fix deadlock on startup and htsmsg queue handling
[pvr.tvh] - fix potential debug error

Was possible that a % in the title/description would result in a failure to
print (crash) due to *printf thinking the % represented a format value.
[pvr.tvh] - change hardcoded timeouts to use config (spotted by Jalle)
[pvr.tvh] - bump to version 0.8.0