Backfill library additions and changes since 1.0

[Centril]

A diff of the standard library, probably just a snapshot of all release notes concatenated would be of interest to me, at least so we can see what it looks like.

Do it :)

[steveklabnik]

@Centril do you still plan on doing this this week? If not, it's going to miss the milestone.

[Centril]

@steveklabnik Probably won't have time for it unfortunately; we can do it in RC2 instead.

[ehuss]

Closing per #232, the scope of the edition guide has changed and will no longer be tracking historical changes.