fixed apibuild.py's generation of "constructors" to be in alphabetical

* doc/apibuild.py, doc/APIconstructors.html, doc/libxml2-refs.xml,
  win32/libxml2.def.src: fixed apibuild.py's generation of
  "constructors" to be in alphabetical order (instead of previous
  random sequence); regenerated resulting files.
diff --git a/win32/libxml2.def.src b/win32/libxml2.def.src
index 705c2ba..9cdde6f 100644
--- a/win32/libxml2.def.src
+++ b/win32/libxml2.def.src
@@ -638,6 +638,7 @@
 xmlCleanupEncodingAliases
 xmlCleanupGlobals
 xmlCleanupInputCallbacks
+xmlCleanupMemory
 xmlCleanupOutputCallbacks
 xmlCleanupParser
 xmlCleanupPredefinedEntities
@@ -1607,6 +1608,7 @@
 xmlStrlen
 xmlStrncasecmp
 xmlStrncat
+xmlStrncatNew
 xmlStrncmp
 xmlStrndup
 xmlStrstr
@@ -1687,6 +1689,8 @@
 xmlTextWriterEndPI
 xmlTextWriterFlush
 xmlTextWriterFullEndElement
+xmlTextWriterSetIndent
+xmlTextWriterSetIndentString
 xmlTextWriterStartAttribute
 xmlTextWriterStartAttributeNS
 xmlTextWriterStartCDATA