Checklist for The Big Update

Stuff we need to do before we're ready for our "make some noise" announcement. @jeswin, feel free to edit this.

# Probably critical

- [x] #59
- [ ] #46
- We know this will be an ongoing project, but we want to get some wins ahead of the release.
- [x] #50
- [x] #62

# Nice to have
- [x] #39
- Having problems returning `null` from `render()` feels weird coming from other frameworks. It'd be nice to knock this out before drawing attention to Forgo.
- [ ] #58
- Marking this because it minimizes "what-about"-ism from prospective users
- [ ] Making the error boundary general-purpose