dustymugs must have made a correction to pseudo_color -- no black background anymore, also add in visualizations for new named color ramps and liink fromST_AsPNNG TOST_COLRMap

git-svn-id: http://svn.osgeo.org/postgis/trunk@11455 b70326c6-7e19-0410-871a-916f4a2858ee