Load Address Balances Last

[leto]

Currently, because my wallet has so many transactions, the wallet startup shows "Loading..." for a long time until balances are calculated. If I go to send a transaction while this is happening and open the Addressbook, it's empty, because it has not been loaded yet.

Loading the addressbook is a very fast operation and should be done before address balances, which should be the very last operation we do on startup.