Provide script helper functions for dealing with time.

[Ilkka Tuohela]

As a wishlist item for devices like Pioneer CDJ decks, which can display playing track position with hour:minutes:seconds resolution, I propose new control output objects:

- track_position_hours is triggered when deck track 'hour' value is changed
- track_position_minutes is triggered when deck track 'minutes' value is changed
- track_position_seconds is triggered when deck track 'seconds' value is changed

In addition, we should provide similar reverse output controls for remaining time, 'track_position_remain_hours', 'track_position_remain_minutes' and 'track_position_remain_seconds'. These are used when 'show remaining track time' value is shown.

While these can be created with a javascript function from track length and track_position, this is something which should not require timers and custom code, I think.

Related signal to implement would be 'track_position_warning', triggered to true when the position of track is within n seconds from end of track, which is configurable in mixxx. Right now the javascript implementation of such functionality can't follow the configured value in mixxx, I believe.

[RJ Skerry-Ryan (rryan)]

Instead of this I think we should just provide good library functions for converting a position CO for a deck into individual components.

[Swiftb0y (swiftb0y)]

Mixxx now uses GitHub for bug tracking. This bug has been migrated to:
https://github.com/mixxxdj/mixxx/issues/6564