Added public member functions to itktubeRidgeExtractor for retrieving different types of ridge information at the current location. And, made a few enhancements to the documentation elsewhere.
Merge remote-tracking branch 'upstream/master' into RetrieveLocalRidgeInformation
Converted double assignment to single to adhere to the style guidelines
Merge pull request #373 from cdeepakroy/RetrieveLocalRidgeInformation

Added functions to itktubeRidgeExtractor for retrieving ridge information at current location