Remove the error element from the XML DTD. It was supposed to be a child

of trace, but I don't think it has ever been emitted since traceroute
was added in r4556.

docs/nmap.dtd

@@ -287,7 +287,7 @@
 			values		CDATA		#IMPLIED
 >
 
-<!ELEMENT trace (hop*, error?) >
+<!ELEMENT trace (hop*) >
 <!ATTLIST trace
       proto   CDATA   #IMPLIED
       port    CDATA   #IMPLIED
@@ -301,11 +301,6 @@
       host    CDATA   #IMPLIED
 >
 
-<!ELEMENT error EMPTY>
-<!ATTLIST error
-     errorstr   CDATA #IMPLIED
->
-
 <!ELEMENT times EMPTY>
 <!ATTLIST times
 	srtt	CDATA	#REQUIRED

docs/nmap.xsl

@@ -758,9 +758,6 @@
         </xsl:when>
       </xsl:choose>
       <li>proto: <xsl:value-of select="@proto" /></li>
-       <xsl:for-each select="error">
-        <li>error: <xsl:value-of select="@errorstr"/></li>
-       </xsl:for-each>
   </ul>
   <table cellspacing="1">
     <tr class="head">