moved nemerical methods back to mlab pending more comprehensive reorg
fix bug in "angles='xy'" support in quiver
Change quiver angles kwarg from radians to degrees
Added an EllipseCollection class to collections.py
Added angles kwarg to quiver, fixed bugs.
fixed last remaining known pytz setup bug
fixed another pytz setup bug; still one remains
fixed a pytz setup bug
adding new pytz
updating pytz and dateutil -- HEAD will be broken temporarily
