Rework how we handle Scenes

[mikeybanez]

We have a number of scene-related events in the pipeline (#98 for both add and remove), which will help a lot now that XSplit 2.8 has unlimited scenes.

However, this means we will have to revisit how we handle scenes. Currently we have two methods for fetching scenes:

1. Scene.getByName: we've already handled duplicate scene names by returning an array
2. Scene.getByIdAsync: this is very dependent on scene index under the hood. For a long time we haven't considered that index is fragile due to how users can simply reorder scenes. Now that adding and deleting scenes is available, index is now a larger source for bugs in scene-sensitive plugins.

Since 1.5.0 is a small release, I'm putting this into 1.6.0 for now. When 1.5.0 is released, let's revisit the requirements to do this. Here are some suggestions for improvement.

• complete the set of scene events from XSplit core: add, remove, move/swap, rename (although the latter isn't relevant to the potential bugs above.)
• let's confer with the core team and see if it is possible to have a unique identifier for scenes. Perhaps we can instead have some sort of Scene.getByUid for better tracking of a scene as users move them around.

[mikeybanez]

Scene add and remove events were accomplished in a different issue, while rename/move events are not currently planned for the application. Therefore it seems that the only scene-related improvement we can do at the moment will be #142.

I'm removing this from 2.3.0.

[mikeybanez]

This issue involves scene rename/reorder events. With the upcoming #165 allowing for scene indexes, is it already possible for consumers to detect name/index changes on their own, @virn ? If not, then do we already have all necessary prerequisites to implement these events in xjs?

(Noting also that #97 is a feature request for rename events.)

[virn]

It's still not possible to detect name/index changes, but I am watching CPPCORE-1048 for this. Which should then allow us to listen to these events.

[mikeybanez]

With the release of 2.7.0, the only remaining scene handling issue should be an index-change event (and a scene rename event: #97)