more work on Relax-NG regenerated the docs updated and augmented the

* relaxng.c: more work on Relax-NG
* doc/*: regenerated the docs
* test/relaxng/* result/relaxng/*: updated and augmented the
  Relax-NG regression tests and results
Daniel
diff --git a/test/relaxng/tutor4_3_6.xml b/test/relaxng/tutor4_3_6.xml
new file mode 100644
index 0000000..f715763
--- /dev/null
+++ b/test/relaxng/tutor4_3_6.xml
@@ -0,0 +1 @@
+<p>a<bold>b<span style="foo">c</span>d</bold>e<italic>f</italic>g</p>