Zecwallet

- Fix crash with shielding
- Add import for t-addresses
- Download memos setting

This version of the SDK adds wallet settings to download none/wallet/all memos

- Performance improvements during syncing and import
- Better monitoring of the mempool

- Perf improvements and bug fixes
- Better support large wallets

This version of Zecwallet Lite SDK now allows you to spend funds with only 1 confirmation ( It previously needed 5 confirmations). This is possible because of a large update on both the client and server that allows the wallet to follow the zcashd blocks more closely.

- Monitors the mempool to detect new blocks or reorgs
- Detect 1-block reorgs immediately
- Pick optimal anchor blocks to send outgoing transactions.

This version of the Zecwallet SDK monitors the mempool for incoming transactions, immediately showing unconfirmed transactions in the tx list.