Add iconvert --attrib to set arbitrary attrib, also allow for more than one --keyword on the command line.
Add iconvert --attrib to set arbitrary attrib, also allow for more than
one --keyword on the command line.


git-svn-id: c3edda122e248ef33995da003806c930f62b9468@488 31904243-a364-42ac-a3db-9305396518ba

lgritz/oiio,jeremyselan/oiio,OpenImageIO/oiio,OpenImageIO/oiio,jeremyselan/oiio,sambler/oiio,bdeluca/oiio,mcanthony/oiio,cwilling/oiio,bdeluca/oiio,sambler/oiio,mcanthony/oiio,lgritz/oiio,sambler/oiio,scott-wilson/oiio,OpenImageIO/oiio,YangYangTL/oiio,bdeluca/oiio,cwilling/oiio,scott-wilson/oiio,bdeluca/oiio,OpenImageIO/oiio,cwilling/oiio,mcanthony/oiio,lgritz/oiio,YangYangTL/oiio,micler/oiio,lgritz/oiio,jeremyselan/oiio,micler/oiio,mcanthony/oiio,scott-wilson/oiio,YangYangTL/oiio,sambler/oiio,scott-wilson/oiio,micler/oiio,YangYangTL/oiio,micler/oiio,cwilling/oiio