Re-enable automatic speaker selection

[Logodaedalus]

Essentially deactivated for now (if not present in config, defaults to monologue, which doesn't really do anything currently) but there's a deactivated StoryAssembler to automatically pick fragments based on who the speaker is as well. This feature was implemented back in...2017? 2016? Then it was abandoned and drifted into "deactivation-by-code-never-executed" over time. It used to have three different modes (narration, monologue, dialogue) and would prioritize fragments that allowed the normal exchange to continue.

Currently you'd need to add

"mode" : {			//what mode dialogue exchange takes place in for the scene
   "type": "dialogue",		//can be dialogue or monologue
   "initiator": "friend1",
   "responder": "protagonist"
},

to your config file, and make sure each fragment has a speaker.

This could probably also come back integrated in with the avatar stuff, as that seems to be where a lot of character logic-y stuff is now.

[Logodaedalus]

We'd also basically need to refactor Character.js:getBestSpeaker() because that's got a bunch of kludges in that currently are called on every fragment, and essentially (AFAIK) always returns the first character in the scene as the "speaker", which is then never used?