Extract additional metadata from XBRL taxonomies

[zschira]

From this issue, we've found that there is additional metadata contained in XBRL taxonomies that will be useful in linking XBRL/DBF data. Specifically, we see use in having the XBRL references, which contain FERC account numbers and form location info, the balance type (credit or debit) and calculations which define relationships between columns (like aggregations). This information can all be pulled out of taxonomies and put into a more usable format.