mention ripemd160 issue
python-ecdsa now support SECP256k1 natively
not needed, shrapnel has coro.backdoor
not needed: paper_key is in its own repository now (https://github.com/samrushing/paper_key)
I'd rather remove unused code than #*@!ing pep8 it
placate the fascist pep8 fundamentalists.

...at least as much as I can handle today.
tweak example