Ability to fetch codes' available values

[dannil]

The implemented model supports fetching the available codes, but not the values that can be used for each of the codes. Implementing this would eliminate the need to manually visit the SCB API website and figuring this out for yourself.

[dannil]

This feature (and more coming which was held back for patch release 0.0.4) will break public API in several classes; a bump to 0.1.0 instead of 0.0.5 is the right way to go.