Voting systems toolbox

I'd like to see this tool support the precise voting system recently
adopted as an option for New Zealand elections. They describe it as
"Single Transferable Vote with counting by Meek's method".
Details at:

<http://www.dia.govt.nz/diawebsite.nsf/wpg_URL/_6a9in6rrle9hmabbdc5q6asj
9c5m2qkqkaomkirj6dtp6qobkd5nmsbadclimm09cecmkqpbkd1nm8_?OpenDocument>

From a brief examination of STV.java, it looks like the differences will be
in details:
* using the specified decimal precision
* using the specified way to resolve ties etc.
* treating informal ballots the specified way

Perhaps the best structure is to create a new class STV_NZ that is parallel
to STV, which implements the New Zealand method. There will also need to
be changes to Table to modify error handling for informal ballots, and to
the command line parameter handling.