PROG Update findfeatures debug apptest, fix MSERExtractor documentation,...

PROG Update findfeatures debug apptest, fix MSERExtractor documentation, update findfeatures application docs, update Blob Algorithm to have same constructor signature as other algorithms. References #4556

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@7319 41f8697f-d340-4b68-9986-7bafba869bb8