Fix potential threading problem if handlers are modified during shutdown (made test fail sometimes)
Resolve problems that make greenmail extremely slow depending on the environment (and thus slow down tests a lot).
The problem is related to the address.getHostName method that does a reverse DNS lookup.
See comments in core for reasons for changes

Also includes some smaller refactorings to make stuff type safe
Remove log4j dependency. Referenced via sfj4j bridge
Compute localhost address only once
Reduce SmtpConnection trace logging to trace loglevel (improves performance)
Reduce SmtpConnection trace logging to trace loglevel (improves performance)
Rename send and receive method
Make tests run faster by reducing number of senders and receivers in multisend/receive test
Correct spelling mistake
Generified multiple classes
ServerSetup always returns 127.0.0.1 as localhost address. Other methods such as InetAddress.getLocalHost().getHostAddress() are unreliable.
Cleanup
Generify
Generify + Cleanup
Make tests run much faster by eliminating unnecessary sleep times. Make tests more understandable
Typos