v2.0.3: JSON Unmarshalling and Marshalling improvements

• Types that have {name} and _{name} entries in their json representation will now be constructed if either / or are present.
• Class properties that are not FHIR values are private once again
• The JSON portion of the generated phpunit tests now assert equivalency between the original representation and the re-encoded version after going through the unmarshal -> marshal routine
• Constructors are now a little bit cleaner, and hopefully easier to read.
• Minor other improvements.