OPTICKS-900: Properly deserialize a data descriptor if it is being deserialized with a data element.

git-svn-id: http://opticks.svn.sourceforge.net/svnroot/opticks/trunk/future@18210 6d0fddd1-9640-0410-91f9-aa98d5e64d34
OPTICKS-1525: PlugInCache does not load properly from a roaming profile

git-svn-id: http://opticks.svn.sourceforge.net/svnroot/opticks/trunk/future@18211 6d0fddd1-9640-0410-91f9-aa98d5e64d34
Added .gitignore files to match svnignore properties