- Combine deconstruction assignment and declaration, and support discards.
- Add wildcards.work.md to track outstanding work.
- Bind each type syntax once in a deconstruction.
- Because tuples may contain declarations, adjust lambda disambiguation
  and adjust parsing of argument lists.
- Diagnose tuple element names on the left of a deconstruction.
- Add relational operators to disambiguating tokens in 7.5.4.2

This is now a semantic restriction (until we decide to remove it).

Plus other changes per code review.

…iew.