ENH: Add test for itkTestingStretchIntensityImageFilter

In order to increase code coverage, add a test for this class.

Change-Id: Icd70253eaad508f7cbc3ec4d8a734ff6c2b6857c
BUG: Not restoring ostream format

Coverity reports:
The next output operation may not expect the stream format state being
altered, resulting in incorrectly formatted output.

Change-Id: I54e4aa65bedaba024ea3f343b72f07415a9a4789
Merge topic 'AddStretchIntensityFilterTest'

8ea974b1 ENH: Add test for itkTestingStretchIntensityImageFilter
Merge topic 'Coverity_RestoreStreamFormat'

a3ae6b87 BUG: Not restoring ostream format