adding the pattern node selection code. Inheried in part from libxslt but

* pattern.c include/libxml/pattern.h: adding the pattern node
  selection code. Inheried in part from libxslt but smaller.
* Makefile.am configure.in include/libxml/xmlversion.h.in:
  integrated the pattern module, made it a configure time option
* xmllint.c: added --pattern to test when doing --stream
Daniel
diff --git a/include/libxml/xmlversion.h.in b/include/libxml/xmlversion.h.in
index dd78b88..fcef1cc 100644
--- a/include/libxml/xmlversion.h.in
+++ b/include/libxml/xmlversion.h.in
@@ -121,6 +121,15 @@
 #endif
 
 /**
+ * LIBXML_PATTERN_ENABLED:
+ *
+ * Whether the xmlPattern node selection interface is configured in
+ */
+#if @WITH_PATTERN@
+#define LIBXML_PATTERN_ENABLED
+#endif
+
+/**
  * LIBXML_WRITER_ENABLED:
  *
  * Whether the xmlWriter saving interface is configured in