First commit of the new Relax-NG validation code, not generally useful

* Makefile.am configure.in relaxng.c include/libxml/relaxng.h:
  First commit of the new Relax-NG validation code, not generally
  useful yet.
* test/relaxng/* result/relaxng/*: current state of the regression
  tests
Daniel
diff --git a/test/relaxng/tutor3_1.rng b/test/relaxng/tutor3_1.rng
new file mode 100644
index 0000000..78d6736
--- /dev/null
+++ b/test/relaxng/tutor3_1.rng
@@ -0,0 +1,12 @@
+<element name="addressBook" xmlns="http://relaxng.org/ns/structure/1.0">
+  <zeroOrMore>
+    <element name="card">
+      <attribute name="name">
+        <text/>
+      </attribute>
+      <attribute name="email">
+        <text/>
+      </attribute>
+    </element>
+  </zeroOrMore>
+</element>