Merge pull request ethereum#1829 from ethereum/dev

release v0.12.0

Merge pull request ethereum#1818 from ethereum/v011x

v0.11 multiple blocks in single slot patch

Merge pull request ethereum#1753 from ethereum/gen-req-fix

fix requirements.txt for bls generator

Merge pull request ethereum#1686 from ethereum/v011x

Release `v0.11.1` to master

Merge pull request ethereum#1686 from ethereum/v011x

Release `v0.11.1` to master

Merge pull request ethereum#1645 from ethereum/dev

Release v0.11.0 into master

Merge pull request ethereum#1589 from ethereum/v010x

Release `v0.10.1` to `master`

Merge pull request ethereum#1561 from ethereum/dev

Release v0.10 to master

Merge pull request ethereum#1545 from ethereum/v09x

Release v0.9.4 to master

Merge pull request ethereum#1507 from ethereum/v09x

Release v0.9.3 to master