minor changes
refactured mapping measure datum

- introduced MappingQuadMeasureDatum class for measures concerning quad
  patterns
- introduced MappingVarMeasureDatum class for measures concerning quad
  pattern variables
refactored metric classes to use new mapping measure classes

- refactored PropertyCompleteness class
- refactored IntensionalConciseness class
updated and refactored measure data sinks

- updated and refactored BooleanTestingSink, DummySink and
  ValueTestingSink
added another intensional conciseness metric test
added extensional conciseness metric and tests
minor whitespace changes in view definitions
minor changes: cleaned imports
added no duplicate statements metric (untested)