Planning: version number incompatibilities between libraries

[LB--]

Since some basic containers will be separate libraries and independently versioned, it is possible for code using one version to need to communicate with code using another version.

In general this can be solved with duck typing and converting between versions as needed.

Needs more thought...

[LB--]

Dependency injection is a really good idea, and perhaps reverse dependency injection may also work in some cases. Both would require duck typing...