super slow pure python brotli decoder, please ignore

ported from brotli-rs to a minimal python subset and now back to standard python (but unpolished) as a side project

usage:

from brotlipython import brotlidec
in = open('test.br', 'rb').read()
outbuf = []
dec = brotlidec(in, outbuf)  # also returns bytes(outbuf) again

or see ./brotlipython.py --help