Release Millboard v0.2.2

[wookay]

@JuliaRegistrator register()

changes
8159f48 : namedtuples, custom types

[JuliaRegistrator]

Registration pull request created: JuliaRegistries/General/7024

After the above pull request is merged, it is recommended that a tag is created on this repository for the registered package version.

This will be done automatically if Julia TagBot is installed, or can be done manually through the github interface, or via:

git tag -a v0.2.2 -m "<description of version>" 6372653975fb092e9f66a5b0f9ecfa035aca9850
git push origin v0.2.2