fixed xmlXPathReturnString to cater for NULL pointer (bug 129561) added

* include/libxml/xpathInternals.h: fixed xmlXPathReturnString
  to cater for NULL pointer (bug 129561)
* globals.c: added comment to suppress documentation warning
* doc/apibuild.py: fixed problem which caused last APIchunkxx.html
  to be lost.  Rebuilt doc/* (including adding APIchunk26.html)
diff --git a/doc/APIchunk10.html b/doc/APIchunk10.html
index 6e13a26..48e2d4f 100644
--- a/doc/APIchunk10.html
+++ b/doc/APIchunk10.html
@@ -33,6 +33,7 @@
 <a href="APIchunk23.html">t-t</a>
 <a href="APIchunk24.html">u-w</a>
 <a href="APIchunk25.html">x-x</a>
+<a href="APIchunk26.html">y-z</a>
 </h2><h2>Letter c:</h2><dl><dt>cae</dt><dd><a href="html/libxml-xmlschemastypes.html#xmlSchemaCheckFacet">xmlSchemaCheckFacet</a><br />
 </dd><dt>calculates</dt><dd><a href="html/libxml-encoding.html#xmlUTF8Size">xmlUTF8Size</a><br />
 </dd><dt>call</dt><dd><a href="html/libxml-encoding.html#xmlCharEncOutFunc">xmlCharEncOutFunc</a><br />
@@ -233,7 +234,6 @@
 </dd><dt>checking</dt><dd><a href="html/libxml-xlink.html#xlinkIsLink">xlinkIsLink</a><br />
 <a href="html/libxml-tree.html#xmlBufferWriteQuotedString">xmlBufferWriteQuotedString</a><br />
 <a href="html/libxml-uri.html#xmlBuildURI">xmlBuildURI</a><br />
-<a href="html/libxml-xmlmemory.html#xmlMemFree">xmlMemFree</a><br />
 <a href="html/libxml-encoding.html#xmlUTF8Strlen">xmlUTF8Strlen</a><br />
 </dd><dt>checkings</dt><dd><a href="html/libxml-valid.html#xmlValidateOneElement">xmlValidateOneElement</a><br />
 </dd><dt>checks</dt><dd><a href="html/libxml-HTMLparser.html#htmlAutoCloseTag">htmlAutoCloseTag</a><br />
@@ -272,6 +272,7 @@
 <a href="html/libxml-tree.html#xmlAddChild">xmlAddChild</a><br />
 <a href="html/libxml-tree.html#xmlAddNextSibling">xmlAddNextSibling</a><br />
 <a href="html/libxml-tree.html#xmlAddPrevSibling">xmlAddPrevSibling</a><br />
+<a href="html/libxml-tree.html#xmlChildrenNode">xmlChildrenNode</a><br />
 <a href="html/libxml-tree.html#xmlDocGetRootElement">xmlDocGetRootElement</a><br />
 <a href="html/libxml-tree.html#xmlDocSetRootElement">xmlDocSetRootElement</a><br />
 <a href="html/libxml-tree.html#xmlElemDump">xmlElemDump</a><br />
@@ -286,6 +287,7 @@
 <a href="html/libxml-tree.html#xmlNodeDumpOutput">xmlNodeDumpOutput</a><br />
 <a href="html/libxml-parserInternals.html#xmlParseElementChildrenContentDecl">xmlParseElementChildrenContentDecl</a><br />
 <a href="html/libxml-parserInternals.html#xmlParseElementContentDecl">xmlParseElementContentDecl</a><br />
+<a href="html/libxml-tree.html#xmlRootNode">xmlRootNode</a><br />
 <a href="html/libxml-valid.html#xmlValidGetPotentialChildren">xmlValidGetPotentialChildren</a><br />
 <a href="html/libxml-valid.html#xmlValidGetValidElements">xmlValidGetValidElements</a><br />
 <a href="html/libxml-xpathInternals.html#xmlXPathNextChild">xmlXPathNextChild</a><br />
@@ -308,7 +310,8 @@
 </dd><dt>cleanly</dt><dd><a href="html/libxml-xmlIO.html#xmlCheckHTTPInput">xmlCheckHTTPInput</a><br />
 </dd><dt>cleans</dt><dd><a href="html/libxml-nanoftp.html#xmlNanoFTPScanProxy">xmlNanoFTPScanProxy</a><br />
 <a href="html/libxml-nanohttp.html#xmlNanoHTTPScanProxy">xmlNanoHTTPScanProxy</a><br />
-</dd><dt>cleanup</dt><dd><a href="html/libxml-threads.html#xmlCleanupThreads">xmlCleanupThreads</a><br />
+</dd><dt>cleanup</dt><dd><a href="html/libxml-globals.html#xmlCleanupGlobals">xmlCleanupGlobals</a><br />
+<a href="html/libxml-threads.html#xmlCleanupThreads">xmlCleanupThreads</a><br />
 <a href="html/libxml-nanoftp.html#xmlNanoFTPCleanup">xmlNanoFTPCleanup</a><br />
 </dd><dt>clear</dt><dd><a href="html/libxml-list.html#xmlListMerge">xmlListMerge</a><br />
 </dd><dt>clears</dt><dd><a href="html/libxml-xmlIO.html#xmlCleanupInputCallbacks">xmlCleanupInputCallbacks</a><br />
@@ -808,4 +811,5 @@
 <a href="APIchunk23.html">t-t</a>
 <a href="APIchunk24.html">u-w</a>
 <a href="APIchunk25.html">x-x</a>
+<a href="APIchunk26.html">y-z</a>
 </h2><p><a href="bugs.html">Daniel Veillard</a></p></td></tr></table></td></tr></table></td></tr></table></td></tr></table></td></tr></table></body></html>