Added possibility of setting an account from which to withdraw the amount. Added appropriate messages. Added config entry to deny finding of offline players by name (can hang the server)

Suggested by @Laynoooor

PS.
Right now, the players will get their money even if the "bank" account is out of money. Will add different settings for this later (i.e if not enough money a) nobody gets any money b) account goes negative c) people get money regardless of the bank's account balance d) people get a proportionately smaller sum).