revid: loop mode

[Alan Noble]

It would be useful for testing for revid to be able to continuously loop over a file input.

This would be invoked either --loop on the command line or via a new NetReceiver mode value Loop (in addition to Normal, Paused or Burst).

Loop mode would not apply to streaming input devices, such as raspivid or geovision.

[Saxon Milton]

Assigned to @Saxon Milton

[Saxon Milton]

This issue is a prerequisite.

[Saxon Milton]

Resolved in PR #354