Fix playback of large recorded mkv files.

CHTSPVFS::SendFileSeek() was returning an error due to 32-bit ssize_t overflow which caused matroska header parsing to fail.
sync API
[pvr.tvh] bump version to 0.9.4
Merge pull request #52 from xhaggi/tvh-bump-api-version

Sync PVR API changes and bump add-on
[pvr.tvh] support ATSC subchannel numbers
[pvr.tvh] update changelog
Merge pull request #51 from johsmi/playrecordingfix

Fix playback of large recorded mkv files.