Merge pull request ethereum#4957 from ethereum/develop_v0425

Merge to release for 0.4.25

Merge pull request ethereum#4148 from ethereum/develop

Merge develop into release for 0.4.24

Merge pull request ethereum#3950 from ethereum/develop

Merge develop into release for 0.4.23

Merge pull request ethereum#3892 from ethereum/develop

Merge develop into release for 0.4.22

Merge pull request ethereum#3678 from ethereum/develop

Merge develop into release.

Merge pull request ethereum#3503 from ethereum/develop

Merge develop into release for v0.4.20.

Merge pull request ethereum#3261 from ethereum/develop

Merge develop into release for 0.4.19

Merge pull request ethereum#3099 from ethereum/develop

Merge develop into release for 0.4.18.

Merge pull request ethereum#2947 from ethereum/develop

Merge develop into release for 0.4.17.

Merge pull request ethereum#2802 from ethereum/develop

Merge develop into release for 0.4.16