Added back the ability to place <iref> elements in locations where th…

…ey will translate to invalid HTML. Avoided invalid HTML by pushing the span up one level, as a previous sibling, when needed. Fixes issue #378.

 - Legacy-Id: 2750

cli/tests/input/draft-v3-features.xml

@@ -519,8 +519,8 @@ foo = bar
       <name>Tables</name>
       <section>
         <name>Bare Table (unnamed, no anchor, with iref)</name>
-	<iref item="Bare Table"/>
         <table>
+	  <iref item="Bare Table"/>
           <thead>
             <tr>
               <th>Column 1</th>

cli/xml2rfc/data/v3.rnc

@@ -723,6 +723,7 @@
        attribute anchor { xsd:ID }?,
        attribute pn { xsd:ID }?,
        name?,
+       iref*,
        thead?,
        tbody+,
        tfoot?

cli/xml2rfc/data/v3.rng

@@ -1629,6 +1629,9 @@
       <optional>
         <ref name="name"/>
       </optional>
+      <zeroOrMore>
+        <ref name="iref"/>
+      </zeroOrMore>
       <optional>
         <ref name="thead"/>
       </optional>

cli/xml2rfc/writers/html.py

@@ -1394,7 +1394,12 @@ def entry(dl, name, value):
     # 
     #    <span class="iref" id="s-Paragraphs-first-1"/>
     def render_iref(self, h, x):
-        return add.span(h, x, classes='iref', id=x.get('pn'))
+        span = build.span(classes='iref', id=x.get('pn'))
+        if h.tag in ['table', ]:
+            h.addprevious(span)
+        else:
+            h.append(span)
+        return span
 
     # 9.28.  <keyword>
     #