Did some refactoring in Java-land: Added package with classes for
complex arithmetic and complex affine transformations to represent the
current view transformation state (the part that java otherwise doesn't
know about).  In the view class, factored out two inner classes, one to
hold the current transformation state, and one to handle touch events.
Now pinch-to-zoom works, and the bitmapper applies the current affine
transformation before passing through the map.