Improve terminology and share set chan

@flahertyb @barnabyc @ermanc @AdamEdgett @tlunter 

After a good brainstorming session yesterday we came up with a few changes. I think this is a much improved terminology. It now uses just 1 channel to update the state and the cursor which is a huge improvement.
`main` as a prefix doesn't mean much, but knowing the previous name I appreciate the difference, although others may not.