itis_sql_to_json.py - parses taxonomic data from itis.gov into a tabular tree encoded in
json. Each node has an associated date. For tips, the date is the year oin which the
species was described. For internal nodes, it is the year that the youngest descendent
+species was described.
-The following are nested test files of increasing size:
+force - a d3 tree viewer, that operates on *.json files produced by itis_sql_to_json.py