show sane main view when no wallet loaded.
show error dialog when wallet could not be loaded.
show wallet up_to_date indicator in title bar.
refactor QETransactionListModel to be more self-contained.
Currently only Electrum seeds are considered valid.
For BIP39 additional dialog is needed.
For SLIP39 multiple mnemonics need to be supported to generate a seed
remove load_wallet from walletDB, route all wallet loading through QEDaemon.
QEDaemon emits walletLoaded and walletRequiresPassword signals. main.qml opens
OpenWallet view when extra user interaction is needed