release 0.16.0

[jeremyandrews]

There's been a lot of changes since 0.15.2, so we need to do a performance regression test and provide some upgrade instructions.

[jeremyandrews]

Performance regression looks good, 0.16.0 is showing ~5% better performance than 0.15.2 (why?)

• https://docs.google.com/spreadsheets/d/1a9VYz6BhabVC6w_gsqMBYyTVrZSQFHBBY5aMqknF2tU/edit#gid=0
• https://docs.google.com/document/d/17iaA0UrR0kE3KRW73DJa2ogwQNH07gSr_pJaxeJLCSA/edit#

[jeremyandrews]

Re-running the performance tests they're more neck and neck, the differences seem to be an artifact of the old AMD Threadripper server I'm using.