Correct error for EOF in “in template” state

Doing `errUnclosedElements(eltPos, "template")` for EOF in the “in
template” state results in the error message “End tag `template` seen, but
there were open elements”, which is all wrong because the actual problem is
that though a `template` end tag was expected, EOF was reached without a
`template` end tag being seen.

So let’s instead when we reach this just report the list of open elements.

Author: sideshowbarker

src/nu/validator/htmlparser/impl/TreeBuilder.java

@@ -1351,7 +1351,7 @@ public final void eof() throws SAXException {
                         break eofloop;
                     }
                     if (errorHandler != null) {
-                        errUnclosedElements(eltPos, "template");
+                        errListUnclosedStartTags(0);
                     }
                     while (currentPtr >= eltPos) {
                         pop();