Introducing cool debug functionality to sigslot library.
When compiled with CAMPVIS_DEBUG, all signals carry additional information on the calling function, file and line. This is realized transparently through some macro magic when client code emits signals through the new emitSignal() method. Unfortunately, there is no way to debug-overload the operator(), hence, while this way of emitting signals remains valid, it cannot write the debug information into the signal handle. To avoid symbol conflicts, _connection_base::emitSignal() and has_slots::emitSignal() had to be renamed to ::processSignal(). refs #384