[cmyth] Add cmyth_timestamp_utc_from_unixtime
[cmyth] Update cmyth_proginfo_delete_recording

This updates cmyth_proginfo_delete_recording to use the different
versions of DELETE_RECORDING.

 1-55: DELETE RECORDING[]:[]<proginfo>
56-58: DELETE RECORDING chanid recstartts [FORCE/NO_FORCE]
59-  : DELETE RECORDING chanid recstartts [FORCE/NO_FORCE [FORGET/NO_FORGET]]

For newer protocol versions, this allows also to force deletion and
allows to rerecord a recording.
[mythtv-cmyth] Update DeleteRecording and add DeleteAndForgetRecording
[mythtv-cmyth] Add menuhook 'Delete and re-record'
[cmyth] Internal EDL

- Adding cmyth_mysql_get_frame_offset(): Return offset for frame
[mythtv-cmyth] Internal EDL

- Demo: Playback with internal EDL (read and seek)
- With null stub for PVR EDL
[mythtv-cmyth] Internal EDL

- Clean code for release
[mythtv-cmyth] Internal EDL

- On skip back then ignore cut
[cmyth] Internal EDL

- Don't return a linear position but positions of frame headers around the mark.
[mythtv-cmyth] Internal EDL

- Use positions of frame headers around the mark instead linear position.
- On skip back then ignore handled cut. (But once passed, don't ignore it anymore)
- General code improvement
[mythtv-cmyth] internal EDL

- Improve code to avoid unexpected case:
  Find the new m_Cut after ignore instead waiting the next seek.
  Remove test &3 because mask could be signed
[mythtv-cmyth] Internal EDL

- Choose larger cut
[mythtv-cmyth] Internal EDL

- Add ADDON setting edl_method_provider (PVR | Internal). Default is PVR.