Multiple cells now selectable at once (can still only edit one at a time...

Multiple cells now selectable at once (can still only edit one at a time though); fixed bug in CnetEditorWindow::readSettings

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@2015 41f8697f-d340-4b68-9986-7bafba869bb8