Add BIP-44 Support

[vishakh]

ConseilJS needs HD wallet support for it to become truly viable for wallet and business use, i.e. from a single cryptographic seed it needs to derive multiple Tezos addresses. Currently it only supports a single Tezos address per seed for file-based wallets and single hard-coded derivation paths for Ledger wallets. If ConseilJS uniformly supported BIP-44 addresses, it could treat file-based and hardware wallets uniformly and become a universal solution for all manners of Tezos wallets.

The list of tasks for this ticket include:

• [ ] Find libraries or implement bespoke functionality to add BIP-44 functionality for Tezos.
• [ ] Devise backwards-compatible changes to file wallets to support BIP-44.
• [ ] Add functionality to sweep the derivation path space for active Tezos addresses for a seed by using linear, quadratic and custom probing.
• [ ] (Optional) Ensure all changes work with Trezor devices as well

A previous description (#43) of this functionality may have relevant information.