show zone name instead of class name; fixes #54
Use pyt file instead of stand-alone tbx for testing.
reference names with scoping; import * isn't helpful
use proper tempdir mechanism which handles construction / destruction automatically.
include bathymetry raster statistics.
Redo testing framework, add new tests and make more robust for future tool additions. With this validation step, python port of modelbuilder tool is complete, and this fixes #53.