PIVOT-922:  Corrections to some of the renderers fixed earlier: the
"toString" methods were not taking into account the possibility of
the data being a pure Image (which should not generate any text).

This is a merge of revision 1523736 from trunk to branches/2.0.x.



git-svn-id: https://svn.apache.org/repos/asf/pivot/branches/2.0.x@1523738 13f79535-47bb-0310-9956-ffa450edef68