Bump version: 5.1.0

Not sure if this is right for the version number but it _feels_ right.

Bump version: 5.0

Bump version: 4.2.2

Bump version: 4.2.1

Bump version: 4.2.0

Bump version: 4.1.1

Bump version: 4.1

Bump version: 4.0.1

Update version to 4.0.0

Bump version: 3.2.1