Docstring tests added
Docstring tests added

Also changed line 209 back to
self.y = self.y - values
For some reason -= operator has problems with automatic  convertion from numpy.float64 to numpy.int64. 
This way works fine .
grzanka/beprof,ant6/beprof,DataMedSci/beprof,DataMedSci/beprof,ant6/beprof