util.PRNG and thus randrange_from_seed_* are not constant over python versions

[tomato42]

the PRNG generates a different keystream on Py2 than it does on Python3, as such methods like randrange_from_seed__trytryagain are not constant over python versions

[tomato42]

we should probably implement two ones, one that behaves like the python2 version even on python3 and one that behaves like the python3 version even on python2