[pvr.tvh] ignore subscriptionStart if video stream details are missing

This fixes a bug where VAAPI sometimes crashes because we try to
initialize it with 0x0 video dimensions
[pvr.tvh] remove SChannel.now and SChannel.next, XBMC doesn't use
them and we needlessy trigger a lot of channel updates whenever
these values change
[pvr.tvh] bump version to 0.9.3
Merge pull request #50 from Jalle19/Gotham

[pvr.tvh] sync Gotham branch with latest changes
Merge branch 'Gotham' into autorec_gotham