Modify show_param input walking to account for multiple data parmaeters.

xref https://github.com/galaxyproject/galaxy/pull/1561
fixes https://github.com/galaxyproject/galaxy/issues/1660

templates/show_params.mako

@@ -1,5 +1,6 @@
 <%inherit file="/base.mako"/>
 <%namespace file="/message.mako" import="render_msg" />
+<% from galaxy.util import listify %>
 <% from galaxy.util import nice_size %>
 
 <style>
@@ -63,13 +64,24 @@
             %elif input.type == "data":
                     <tr>
                         ${inputs_recursive_indent( text=input.label, depth=depth )}
+                        <td>
+                        %for i, element in enumerate(listify(param_values[input.name])):
+                        %if i > 0:
+                        ,
+                        %endif
+                        %if element.history_content_type == "dataset":
                         <%
-                            hda = param_values[input.name]
+                            hda = element
                             encoded_id = trans.security.encode_id( hda.id )
                             show_params_url = h.url_for( controller='dataset', action='show_params', dataset_id=encoded_id )
                         %>
-                        <td><a class="input-dataset-show-params" data-hda-id="${encoded_id}"
-                               href="${show_params_url}">${hda.name | h}</a></td>
+                        <a class="input-dataset-show-params" data-hda-id="${encoded_id}"
+                               href="${show_params_url}">${hda.name | h}</a>
+                        %else:
+                        ${element.hid}: ${element.name | h}
+                        %endif
+                        %endfor
+                        </td>
                         <td></td>
                     </tr>
              %elif input.visible: