Order of children matters

[scf1984]

One should have control over the order of children. Currently they are ordered in exportChildren by their Generateds class.
This is important, for example, for math prefix notation where / 1 2 is not the same as / 2 1.

[ricksladkey]

My project was a port to Python3 before the parent project had been ported. I haven't tested it, but the parent project now claims to support Python3, so you could check whether that version suits your needs.