moving sknano.core.testing to sknano.testing.

Since the testing package imports modules outside of the core package
it belongs outside of core to prevent recursive imports
updating module imports of testing package
adding testing sub-package to list of sub-packages
adding testing sub-package to list of sub-packages
removing _graphenes and _nanotubes modules
adding/updating new structures class modules
fixing module import
removing _atoms_converter module
implementing all special methods for comparison operations.

Using the @total_ordering decorator does not seem to override the
numpy superclass methods, causing comparisons to fail for ones not
implemented.
removing import and use of @total_ordering decorator
updating tests
fix module imports
updating the method call to clip_bounds using a region volume object
replacing function name to pluralize strings
updating generator tests
small change
removing debugging print statement
Lots of changes and updates to the geometric_shapes packages.

Implemented the GeometricTransformMixin class.
Added new methods and properties to the GeometricRegions base.
Several other development changes.
adding empty method for computing a reflection transform
pass the vector __array__ to the rezero method and not just self.