Design an improved client API for scripted scope overlays.

[Scrivener07]

As of now, LAER is the only mod using the API for scripted scopes. When I wrote the API it was to suit the needs of LAER so it is very single purposed.
With the huge improvements I made to Overlays Framework I want bring these changes into Scope Framework. But these changes will break the scripts when I move the existing client functions/events to a proper client API. The author of LAER has agreed to support an update for my breaking changes, so now I am free to make these improvements.

This is the "API" I intend to replicate in Scopes Framework. https://github.com/Scrivener07/FO4_Overlays/blob/1baea3e6cc0100d1bac09afc53f4b5b8bbb9be67/Data/Scripts/Source/FO4_Overlays/Fallout/Overlays/Client.psc

I believe that the Get/Set/Invoke and Open/Close events are generic enough to be future proof.