DistanceIsMetric Method 
Name  Description  

IsMetric(FuncDouble, Double, Double) 
Checks whether a function is a real metric distance, i.e. respects
the triangle inequality. Please note that a function can still pass
this test and not respect the triangle inequality.
 
IsMetric(FuncInt32, Int32, Double) 
Checks whether a function is a real metric distance, i.e. respects
the triangle inequality. Please note that a function can still pass
this test and not respect the triangle inequality.
 
IsMetricT(IDistanceT) 
Checks whether a function is a real metric distance, i.e. respects
the triangle inequality. Please note that a function can still pass
this test and not respect the triangle inequality.
