Allow the exportation of extended public key

[Sword-Smith]

When I try to export an extended public key from my ledger, I can only find what in Bitcoin terms are called an compressed public key, a public key starting with 02 or 03. I would like the extended public key, so I can derive addresses without using the Ledger.

This requires that the Ledger can derive tz2 addresses as specified in #158

Se also the Stack Exchange issue on this
https://tezos.stackexchange.com/questions/2869/can-i-export-an-ecdsa-xpub-from-my-ledger

[mikereinhart]

Does this request change at all in light of the answer I've provided on #158?

[Sword-Smith]

Does this request change at all in light of the answer I've provided on #158?

I would have to look into that.

[Sword-Smith]

Does this request change at all in light of the answer I've provided on #158?

I could not get this to work.