add a theme function for altered term links

This module could use a theme function for the term output.
For instance, the current output if image + name is chosen is the image, a BR, and the term:

      $tname = $show_name ? ('<br />'. taxonomy_image_tt("taxonomy:term:$term->tid:name", $term->name)) : NULL;

Because this isn't in a theme function there's no way to get rid of the BR without modifying the module code directly.