Unified squashed result of google merge.

[wiseoldduck]

For your consideration. Kinda raw.

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[muukii]

What's this PR?
These changes are improved for Google's products?
It's interesting and it looks there are some new features.

[wiseoldduck]

@muukii more or less. Several of the contributors work at Google now and for various reasons largely stopped contributing a couple years ago. We are recently working with Pinterest to restart that, and to bring in a lot of the improvements we made in the meantime.