Interfaces for creating new statistics and metrics algorihms.

Create a new Metrics

1. Create a new module and set StatisticsAPI and GraphAPI as dependencies.
2. Create a new builder class by implementing StatisticsBuilder
3. Add @ServiceProvider annotation to your builder, that it can be found by the system. Set StatisticsBuilder as the annotation parameter.
4. Create a new class that implements Statistics. Write you code in the execute() method.
5. Create a new class implementing StatisticsUI and add @ServiceProvider annotation as well.
6. In both StatisticsBuilder and StatisticsUI, return your Statistics class object for the getStatisticsClass() method.

To let your export task be cancelled and its progress watched, implement LongTask interface.