Sensor.h: 2011-08-22 Steven Lambright - The DEM cube now uses a...

Sensor.h: 2011-08-22 Steven Lambright - The DEM cube now uses a UniqueIOCachingAlgorithm(5). This will probably behave better in all cases. Fixes #364 

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@3081 41f8697f-d340-4b68-9986-7bafba869bb8