zec-qt-wallet v0.4.3: Auto shield t-Address change

zec-qt-wallet can now send the change from your t-Address transactions into sapling addresses automatically!

Opt-in from the settings page, and zec-qt-wallet will send any change from your t-Addr -> t-Addr or t-Addr -> Sapling transactions into your sapling address instead of sending it back to a t-Address.