Parse incoming and announce outgoing fidelity bond messages
Fidelity bond proof messages will be checked and added to the internal
database just like offers. Such messages are not announced in public
but only directly to takers who ask for them, this is because the
signature proofs must commmit to the maker's and taker's IRC nicknames
in order to avoid replay attacks.
To facilitate easier management by users and to
follow generally accepted standards, this PR moves
the following all to user home directory, subdir
.joinmarket :
joinmarket.cfg file
wallets/ directory
logs/ directory
cmtdata/ directory
commitmentlist file
User can override location with --datadir option.
An info message is added on startup showing location.