Repeat-One should use loop points where supported

[mmontag]

Follow up to #51. Some formats have native support for looping, i.e. NSF files that run forever, or MIDI with loop points.

Repeat-One mode should take advantage of this, i.e. Repeat-One should have multiple effects:

• Repeating
  • Lock the sequencer to the current song (advancing the sequencer restarts the song; already implemented)
• Looping
  • Disable auto-advance when player position reaches end of song. Slider handle should stick at the end of the slider range
  • Enable looping behavior within the player engines that support it

These are two distinct behaviors, but I think it makes sense to link them together under Repeat-One.

[zaphod77]

repeat one only works for stuff already on the site. not for drag and drop files.

as for looping there should be a "loop count" feature, with a few options to pick from, one of which is infinite, and an option to fade after the loopcount expires.