DOC: itk::statistics -> itk::Statistics.

Change-Id: I3ea191ae4fa87fb076346f4c481cc4324acc9481
BUG: Don't print to std::cout in PrintSelf

Use the provided stream to PrintSelf.

Change-Id: I8ce9a608c31e76f3747fd02ab04a461cfd4bfe30
Merge topic 'PrintSelfNotTostdcout'

d9dc47de BUG: Don't print to std::cout in PrintSelf
Merge topic 'itkstatistics'

fe43469a DOC: itk::statistics -> itk::Statistics.