adding xml:id draft support adding 4 first regression tests Daniel

* SAX2.c include/libxml/tree.h: adding xml:id draft support
* Makefile.am test/xmlid/id_tst* result/xmlid/id_tst*: adding
  4 first regression tests
Daniel
diff --git a/result/xmlid/id_tst2.xml b/result/xmlid/id_tst2.xml
new file mode 100644
index 0000000..33ee896
--- /dev/null
+++ b/result/xmlid/id_tst2.xml
@@ -0,0 +1,6 @@
+Object is a Node Set :
+Set contains 1 nodes:
+1  ELEMENT foo
+    ATTRIBUTE id
+      TEXT
+        content=bar