Added an ObliqueDetectorResolution band to phocube. This is an improved...

Added an ObliqueDetectorResolution band to phocube.  This is an improved approximation to the standard DetectorResolution band.  References #476

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@7069 41f8697f-d340-4b68-9986-7bafba869bb8