Added set_namespace() to Node

* Added unit test for namespace

docs/valadoc/Makefile.am

+SUBDIRS=
+
 # inspired by folks' documentation Makefile.am
 
 # distclean_dirs? 

gxml/BackedNode.vala

@@ -104,14 +104,14 @@ namespace GXml {
 		{
 			for (Xml.Ns *cur = node->ns_def; cur != null; cur = cur->next) {
 				if ((string) cur->prefix == prefix && (string) cur->href == uri) {
-					this.node->ns = cur;
+					node->set_ns (cur);
 					return true;
 				}
 			}
 			// Not found in this node, searching on root element
 			for (Xml.Ns *cur = owner_document.document_element.node->ns_def; cur != null; cur = cur->next) {
 				if ((string) cur->prefix == prefix && (string) cur->href == uri) {
-					this.node->ns = cur;
+					this.node->set_ns (cur);
 					return true;
 				}
 			}

test/GXmlTest.vala

@@ -31,6 +31,7 @@ class GXmlTest {
 		NodeTest.add_tests ();
 		ElementTest.add_tests ();
 		AttrTest.add_tests ();
+		NamespaceTest.add_tests ();
 		NodeListTest.add_tests ();
 		TextTest.add_tests ();
 		CharacterDataTest.add_tests ();

test/Makefile.am

@@ -31,6 +31,7 @@ sources = \
 	NodeTest.vala \
 	ElementTest.vala \
 	GXmlTest.vala \
+	NamespaceTest.vala \
 	NodeListTest.vala \
 	TextTest.vala \
 	ValaLibxml2Test.vala \