Auto-advance and Canvas segments

[mikeapp]

Original Issue

IIIF/api#1632

Background
The auto-advance behavior is defined in the Alpha draft as being applied when reaching the end of a Canvas with a duration.

Issue
Ranges may reference parts of Canvases and there are situations in which it may be desirable to have playback auto-advance from one part to the next.

An example provided during our requirements gathering was that of an interview recorded on existing gaps between other recordings spread across a cassette tape. As a content publisher I might wish to define a Range that will auto-advance between the Canvas segments so that users can listen to the interview without manually advancing the playback.

Solution
Allow the auto-advance behavior to apply to segments of Canvases within a Range.

[azaroth42]

From TRC discussion, the difference with Alpha is https://preview.iiif.io/api/image-prezi-rc2/api/presentation/3.0/#behavior:

When the client reaches the end of a Canvas, or segment thereof as specified in a Range, with a duration dimension that has this behavior, it should immediately proceed to the next Canvas or segment and render it.

e.g. if a Range includes a segment of a Canvas (1:00 to 1:45 of the 5:00 total canvas) then it should auto-advance, as the end of the segment has been reached, and thus the auto-advance would be triggered. Previously it would not have triggered as the end of the canvas (at 5:00) was not reached.

[azaroth42]

Issue 17 (Auto-advance and Canvas segments)

+1: 31 [aisaac awead azaroth42 beaudet cubap emulatingkat gigamorph hadro irv jbhoward-dublin jonhartzler joshuago78 jpstroop jronallo jtweed julsraemy jwd kzhr markpatton mattmcgrattan mcwhitaker mikeapp mixterj regisrob rentonsa rsinghal scossu sredick tomcrane tpendragon zimeon]
0: 0 []
-1: 0 []

Result: 31 / 31 = 1.00

Super majority is in favor, issue is approved