Merge pull request argotorg#4148 from ethereum/develop

Merge develop into release for 0.4.24

Merge pull request argotorg#3950 from ethereum/develop

Merge develop into release for 0.4.23

Merge pull request argotorg#3892 from ethereum/develop

Merge develop into release for 0.4.22

Merge pull request argotorg#3678 from ethereum/develop

Merge develop into release.

Merge pull request argotorg#3503 from ethereum/develop

Merge develop into release for v0.4.20.

Merge pull request argotorg#3261 from ethereum/develop

Merge develop into release for 0.4.19

Merge pull request argotorg#3099 from ethereum/develop

Merge develop into release for 0.4.18.

Merge pull request argotorg#2947 from ethereum/develop

Merge develop into release for 0.4.17.

Merge pull request argotorg#2802 from ethereum/develop

Merge develop into release for 0.4.16

Merge pull request argotorg#2709 from ethereum/updateChangelog

Update changelog.