Merge pull request ethereum#6381 from ethereum/develop

Merge develop into release for 0.5.7

Merge pull request ethereum#6269 from ethereum/develop

Merge develop into release for 0.5.6

Merge pull request ethereum#6188 from ethereum/develop

Release 0.5.5

Merge pull request ethereum#5975 from ethereum/develop

Release 0.5.4

Merge pull request ethereum#5836 from ethereum/develop

Merge develop into release for 0.5.3.

Merge pull request ethereum#5697 from ethereum/develop

Merge develop into release for 0.5.2

Merge pull request ethereum#5571 from ethereum/develop

Version 0.5.1

Merge pull request ethereum#5416 from ethereum/develop

Merge develop into release for 0.5.0

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