Fix failing cpp tests
Fix failing cpp tests

- Update the tests for KeyExtractor because it now includes
  SpectralWhitening in its processing chain

- Add a test for diamond shape where A->B->C and A->C

MTG/essentia,carthach/essentia,carthach/essentia,MTG/essentia,carthach/essentia,MTG/essentia,MTG/essentia,carthach/essentia,MTG/essentia,carthach/essentia