Updated documentation for SensorInfoWidget, TargetBodyList, and...

Updated documentation for SensorInfoWidget, TargetBodyList, and TargetInfoWidget in preparation for merge from IPCE into ISIS.  Fixes #4007, #4065

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/branches/ipce@6840 41f8697f-d340-4b68-9986-7bafba869bb8