As per BIP44, 20 addresses are checked for transactions, not just the
first one.
Show the last account only if used or named.
If all accounts are used, prompt for password to create new one.
Fixes#1128
This should speed up synchronization / restoration of large wallets.
Wallets are written only when they switch to up_to_date state, or
when stop_threads() is called when closing the daemon, or when
a command line command finishes.
Proper fix for #1525.
Using python's GC module, I've verified that the daemon, when running,
now releases all verifiers, synchronizers and wallets - all the resources
we care about releasing.
The synchronizer's work is done from the network proxy's main loop.
A minor problem with the old synchronizer was that it considered itself
out of date if the network was out of date. This was too generic: the
network can have pending requests unrelated to the synchronizer. This
resulted in the synchronizer often unnecessarily flipping the wallet
between up-to-date and not-up-to-date, and causing unnecessary calls
to wallet.save_transactions(). This was observable when opening the
network dialog box: frequently just opening it would cause a wallet
status change and transaction flush, simply because the network dialog
sends a get_parameters() request. This rework of the synchronizer does
not have that issue.
