Remove unused methods from DisplayColumn, refactor

Author: labkey-adam

laboratory/src/org/labkey/laboratory/query/EnterResultsDisplayColumn.java

@@ -10,10 +10,14 @@
 import org.labkey.api.exp.api.ExperimentService;
 import org.labkey.api.util.PageFlowUtil;
 import org.labkey.api.view.ActionURL;
+import org.labkey.api.writer.HtmlWriter;
 
 import java.io.IOException;
 import java.io.Writer;
 
+import static org.labkey.api.util.DOM.TD;
+import static org.labkey.api.util.DOM.cl;
+
 /**
  * User: bimber
  * Date: 11/6/12
@@ -57,8 +61,8 @@ public void renderGridCellContents(RenderContext ctx, Writer out) throws IOExcep
     }
 
     @Override
-    public void renderGridHeaderCell(RenderContext ctx, Writer out, String headerClass) throws IOException
+    public void renderGridHeaderCell(RenderContext ctx, HtmlWriter out, String headerClass)
     {
-        out.write("<td class=\"labkey-column-header\"></td>");
+        TD(cl("labkey-column-header")).appendTo(out);
     }
 }