This makes it easier to use the filter stuff from other code, but it's
also turning it into more of a spaghetti nightmare.  Might not be
worth continuing down this path.

This is mostly just intended to make a simple filter example shorter.

This converts data into big Numpy arrays and lets the user-provided
function process as much as they'd like at a time.

Any other module (in this case, nilmdb -> datetime_tz -> pytz -> gettext)
that does an "import copy" would pull in the copy.py, if it's in the
current working directory.  Python is dumb...

Added setup.py and other build tools like versioneer.

Split functionlaity into modules so that new filters are easier to
write.