In mask, made default MASK parameter work when FROM cube has multiple bands....

In mask, made default MASK parameter work when FROM cube has multiple bands. Updated Documentation. Added examples. Fixes #1871.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@5736 41f8697f-d340-4b68-9986-7bafba869bb8