Add BREAD_CRUMB_TRAIL.

This feature enables recursive printing of the bread crumbs for any
page, rather than just printing the parent group.

src/config.xml

@@ -3358,6 +3358,14 @@ to be found in the default search path.
 <![CDATA[
 If the \c DOT_CLEANUP tag is set to \c YES doxygen will
 remove the intermediate dot files that are used to generate the various graphs.
+]]>
+      </docs>
+    </option>
+    <option type='bool' id='BREAD_CRUMB_TRAIL' defval='0'>
+      <docs>
+<![CDATA[
+If the \c BREAD_CRUMB_TRAIL tag is set to \c YES then the complete bread crumb
+trail for a page will be displayed rather than just the root group.
 ]]>
       </docs>
     </option>

src/util.cpp

@@ -6349,26 +6349,40 @@ void addRefItem(const QList<ListItemInfo> *sli,
   }
 }
 
-void addGroupListToTitle(OutputList &ol,Definition *d)
+bool recursivelyAddGroupListToTitle(OutputList &ol,Definition *d,bool root,bool shouldRecurse)
 {
   GroupList *groups = d->partOfGroups();
   if (groups) // write list of group to which this definition belongs
   {
+    if (root) {
       ol.pushGeneratorState();
       ol.disableAllBut(OutputGenerator::Html);
       ol.writeString("<div class=\"ingroups\">");
+    }
     GroupListIterator gli(*groups);
     GroupDef *gd;
-    bool first=TRUE;
+    bool first=true;
     for (gli.toFirst();(gd=gli.current());++gli)
     {
+      if (shouldRecurse && recursivelyAddGroupListToTitle(ol, gd, false, shouldRecurse)) {
+        ol.writeString(" > ");
+      }
       if (!first) { ol.writeString(" &#124; "); } else first=FALSE;
       ol.writeObjectLink(gd->getReference(),
           gd->getOutputFileBase(),0,gd->groupTitle());
     }
+    if (root) {
       ol.writeString("</div>");
       ol.popGeneratorState();
     }
+    return true;
+  }
+  return false;
+}
+
+void addGroupListToTitle(OutputList &ol,Definition *d)
+{
+  recursivelyAddGroupListToTitle(ol,d,true,Config_getBool("BREAD_CRUMB_TRAIL"));
 }
 
 void filterLatexString(FTextStream &t,const char *str,