wip/py-ptyx 20.5 NetBSD

pTyX is a LaTeX precompilator, written in Python. pTyX enables to generate LaTeX documents, using custom commands or plain python code. One single pTyX file may generate many latex documents, with different values. I developped and used pTyX to make several different versions of a same test in exams,for my student, to discourage cheating. Since it uses sympy library, pTyX has symbolic calculus abilities too.