Dangling transaction handling for B2B MSGSNT
Introduced a better interface to the transaction/request maps.
onB2BMSGSNT erased transaction from wrong cache.
Added error logging.
The global BrokerSettings objects says what's wrong, not only throw.
Removed unnecessary benchmark code
Moved env_vars to root and annotated the variables.
`cabal init`.
Implemented configuration module
Protocol implementation + unit tests for it
Test suite integration with cabal
IPC threads, some config changes
Internal concurrency model written.

Incoming/outgoing threads, center thread etc.
fastcgi dependency
Message relay and remote brokers need to know the sender's user name

Conflicts:
	doc/protocols/message-broker-message-relay.mkd
Added sender field for B2B and message-relay protocols
Web client protocol specification (on top of HTTP)
Polling details added.
Added DELCHAN-DELTDCHAN command for message-relay
Replaced parsec by attoparsec