- Support constant records. Fix #2337.
- Support empty and one-positional-field records. Fix #2386.
- Re-add support for positional field getters Fix #2388.
- Specify the behavior of `toString()`. Fix #2389.
- Disambiguate record types in `on` clauses. Fix #2406.

# Conflicts:
#	working/0546-patterns/records-feature-specification.md

There should be no meaningful changes. I just:

- Fixed some misspellings.
- Used Markdown style consistent with the rest of the doc.
- Re-worded things to, I hope, read a little more naturally.
- Removed the parenthetical on identical() in a const context because
  that felt a little too academic.

Specify the evaluation order of fields.