CIP1852 - HD Wallets for Cardano

This is a port of which was originally written for Jormungandr. This version of the document is for Haskell Shelley and also uses the CIP document structure

This is a slight awkward CIP because it’s called CIP1852 despite the fact we definitely don’t have 1852 CIPs. The reason this name was chosen is because the CIP process didn’t exist at the time this document was written (so there was no way to know which number to use), so instead I just picked the year Ada Lovelace died (to match the fact we used 1815 for her date of birth in the cointype field). This matches the fact that in Bitcoin, the purpose derivation index matches the BIP number for the proposal that describes it.