Add python.2 implementation

Add python.2 implementation

This commit adds a new Python 3 implementation of MAL. This
implementation passes all non-optional tests, with the exception
that the travis test script doesn't like the period in the
directory name. During development, this was called "py3" and
it passed Travis tests.

This implementation is different from the main python implementation.
First, it heavily uses type annotations making for a code style
more similar to Java. Second, it uses the Arpeggio parser library
to parse MAL syntax.

This commit also includes unit tests that show roughly the order
of things that were interactively tested and debugged during
development.