[css2] Now allows PNG

--HG--
extra : convert_revision : svn%3A73dc7c4b-06e6-40f3-b4f7-9ed1dbc14bfc/trunk%401754

Author: ianbjacobs

css2/bin/html2ps

@@ -487,6 +487,7 @@ $geturl=$package{'geturl'};
 $ulanch="f";
 $f=72/2.54;
 $giftopm="giftopnm" if($package{'netpbm'});
+$pngtopm="pngtopnm" if($package{'netpbm'});
 $giftopm="giftoppm" if($package{'pbmplus'});
 
 for(keys %option){eval "\$opt_$_='$option{$_}' if(!defined \$opt_$_)"};
@@ -3628,6 +3629,8 @@ sub pictops {
   } elsif($package{'pbmplus'} || $package{'netpbm'}) {
     if($pic=~/^GIF/) {
       &run("$giftopm $scr");
+    } elsif ($pic=~/^.PNG/) {
+      &run("$pngtopm $scr");
     } else {
       &run("anytopnm $scr");
     }