Expands the test suite to include two more CCDAs for parsing tests (from
EMERGE and NIST) since the HL7 sample doesn't exercise the full
parser; also adds a generation test based on the NIST sample
Updates to the C32 parser to better deal with some real-world data from the e-MDs EMR
Improves parsing of free-text medication signatures. In the process, improves
the implementation of val() [for extracting the value of an XML node]
and adds a new function to xml.js for getting a particular tag
without recursively descending.