move the TODO as comments as the function while not finished are usable

* xmlsave.c: move the TODO as comments as the function while not
  finished are usable as-is
* xmlschemas.c include/libxml/xmlerror.h: patch from Kasimier Buchcik
  implementing union
* test/schemas/union_0_0.x* result/schemas/union_0_0*: added example
* python/Makefile.am: applied fix from Mike Hommey
Daniel
diff --git a/xmlsave.c b/xmlsave.c
index 583fb58..1a60a31 100644
--- a/xmlsave.c
+++ b/xmlsave.c
@@ -1265,6 +1265,8 @@
  * @doc:  a document
  *
  * Save a full document to a saving context
+ * TODO: The function is not fully implemented yet as it does not return the
+ * byte count but 0 instead
  *
  * Returns the number of byte written or -1 in case of error
  */
@@ -1274,7 +1276,6 @@
     long ret = 0;
 
     xmlDocContentDumpOutput(ctxt, doc);
-    TODO /* compute ret */
     return(ret);
 }
 
@@ -1284,6 +1285,8 @@
  * @node:  a document
  *
  * Save a subtree starting at the node parameter to a saving context
+ * TODO: The function is not fully implemented yet as it does not return the
+ * byte count but 0 instead
  *
  * Returns the number of byte written or -1 in case of error
  */
@@ -1293,7 +1296,6 @@
     long ret = 0;
 
     xmlNodeDumpOutputInternal(ctxt, node);
-    TODO /* compute ret */
     return(ret);
 }