message: Add CHANGELOG entriesy for senderAddress -> signerAddress
diff: types as well as `isValidBuilder` and `parseWasmData` functions.
  - @cosmjs/cosmwasm: Add `CosmWasmClient.getTx` method for searching by ID and
  remove such functionality from `CosmWasmClient.searchTx`.
  +- @cosmjs/cosmwasm: Rename `SigningCosmWasmClient.senderAddress` to
  + `.signerAddress`.
  - @cosmjs/cosmwasm-stargate: Add new package for CosmWasm Stargate support.
  - @cosmjs/crypto: Change `Secp256k1Keypair` from tagged type to simple
  interface.
  - @cosmjs/launchpad: Add `SigningCosmosClient.appendSignature` method creating
  transactions with multiple signatures.
  - @cosmjs/launchpad: Add support for undefined memo in `makeSignDoc`.
  +- @cosmjs/launchpad: Rename `SigningCosmosClient.senderAddress` to
  + `.signerAddress`.
  - @cosmjs/launchpad-ledger: `LedgerSigner.sign` method renamed `signAmino`.
  - @cosmjs/proto-signing: Add new package for handling transaction signing with
  protobuf encoding.
  