Retro-bip-utils

- Add support for DASH coin (both Bip44 and Bip49 are supported).
- Add *key_helper* module for checking if a key is private or public compressed/uncompressed.
- Add error checking to classes that generate addresses (`P2PKH`, `P2SH`, `P2WPKH`, `EthAddr`, `XrpAddr`). They now raise a `ValueError` exception if the provided key is not valid
- *WIF* module checks for key validity when encoding; when decoding, it checks if the resulting key is valid

- Redesign architecture to make easier to add new coins
- Add support for the following coins:
- Litecoin
- Dogecoin
- Ethereum
- Ripple

- Add possibility to create a `Bip32`, `Bip44`, `Bip49` and `Bip84` object from an extended key
- Rename `Bip44Base.Chain` to `Bip44Base.Change`
- Rename `Bip44Chains`to `Bip44Changes`
- Added some helper methods to `Bip44Base` (`IsMasterLevel`, `IsPurposeLevel`, `IsCoinLevel`, `IsAccountLevel`, `IsChangeLevel` and `IsAddressIndexLevel`)

- Fix *bip39* module (`self` in `staticmethod`)

Included modules:
- BIP-0039
- BIP-0032 with path parser
- BIP-0044, BIP-0049 and BIP-0084
- P2PKH address generation
- P2SH address generation
- P2WPKH address generation
- WIF encoder/decoder
- base58 encoder/decoder