[NEW PORT] devel/py-cppy: Fast implementation of the Cassowary constraint solver

A small C++ header library which makes it easier to write Python extension
modules. The primary feature is a PyObject smart pointer which automatically
handles reference counting and provides convenience methods for performing
common object operations.

WWW: https://pypi.python.org/pypi/cppy

To be used with math/py-kiwisolver

Approved by: tcberner (mentor)
Differential Revision: https://reviews.freebsd.org/D24369