added split.stop(tag) functionality, MonitoringInterceptor changed accordingly
correct behaviour, tagged stop calls normal stopwatch.addSplit(split) which is better for concurrency, respects state of the simon, etc...
extended split.stop(subsimon) javadoc + forgotten option for single 'failure' subsimon for MonitoringInterceptor
small example fixes
StopwatchTemplate merged with AbstractStopwatchSource - this spawned more changes, mostly around introducing StopwatchSource interface