Continued PDF progress. Note: Currently not functional, but code is largely in place.
Merge branch 'master' of https://github.com/CaKlassen/DogSweater into Eric
- finished implementing the feature where Dimension instances can have an expression used to calculate its default value (defaultValueExpression).
    - Dimension instances from a Dimensions instance can use the expression to compute their default value
        - this is necessary because other Dimension values may be involved in the calculations