implement new check_type function
adding new modules defining data structures for math
updating docstrings
define __docformat__
adding new module to play with creating new data structures that subclass ndarray
implement new Point class for Atom coordinates
update docstring
fix bug in function def which still had the `self` argument
updating call to check_type function using new kwarg for allowed_types
adding functions to rezero values that are small, negative numbers
implement Vector class for the atom position and velocity vectors
fix call to check_type
updating setup for release of v0.2.22