Added
* `AccountId.aliasKey`, including `AccountId.[to|from]String()` support.
* `[PublicKey|PrivateKey].toAccountId()`.
* `aliasKey` fields in `TransactionRecord` and `AccountInfo`.
* `nonce` field in `TransactionId`, including `TransactionId.[set|get]Nonce()`
* `children` fields in `TransactionRecord` and `TransactionReceipt`
* `duplicates` field in `TransactionReceipt`
* `[TransactionReceiptQuery|TransactionRecordQuery].[set|get]IncludeChildren()`
* `TransactionReceiptQuery.[set|get]IncludeDuplicates()`
* New response codes.
* Support for ECDSA SecP256K1 keys.
* `PrivateKey.generate[ED25519|ECDSA]()`
* `[Private|Public]Key.from[Bytes|String][DER|ED25519|ECDSA]()`
* `[Private|Public]Key.to[Bytes|String][Raw|DER]()`
Deprecated
* `PrivateKey.generate()`, use `PrivateKey.generate[ED25519|ECDSA]()` instead.