copy form "btcutil/hdkeychain/extendedkey.go", delete some unused function and change some functions to adapt Dipperin.

new wallet manager.

ParseDerivationPath converts a user specified derivation path string to the internal binary representation.

wallet status.

wallet status.

refresh wallet nonce in the wallet manager timely.

establish walletdefault wallet event channel is 0, so there will be an problem if it is 0.

remove wallet.

open wallet.

DefaultBaseDerivationPath is the base path from which custom derivation endpoints are incremented.

DefaultLedgerBaseDerivationPath is the base path from which custom derivation endpoints are incremented.

DefaultRootDerivationPath is the root path to which custom derivation endpoints are appended.

record wallet backend event.

DerivationPath represents the computer friendly version of a hierarchical deterministic wallet account derivaion path.

wallet event type.