collections reform part 2
Update 0000-collections-reform-part-2.md
Update 0000-collections-reform-part-2.md
Update 0000-collections-reform-part-2.md
v2.1
Merge branch 'collections2' of https://github.com/Gankro/rfcs into collections2
Add drain, and link to WIP implementations.
code review
Merge pull request #1 from cgaebel/drain

Add drain, and link to WIP implementations.
Remove Entry Deref
Merge branch 'collections2' of https://github.com/Gankro/rfcs into Gankro-collections2
RFC 509 is Collections reform part 2
Merge branch 'Gankro-collections2' into HEAD