more fixes and extending the tests coverage more hardeing of APIs skip

* gentest.py testapi.c: more fixes and extending the tests coverage
* xmlwriter.c list.c: more hardeing of APIs
* doc/apibuild.py: skip testapi.c when scanning the C files.
Daniel
diff --git a/gentest.py b/gentest.py
index 1468b87..45bedfa 100755
--- a/gentest.py
+++ b/gentest.py
@@ -234,8 +234,9 @@
     return res
 
 known_param_types = [ "int", "const_char_ptr", "const_xmlChar_ptr",
-   "xmlParserCtxtPtr", "xmlDocPtr", "filepath", "fileoutput" ,
-   "xmlNodePtr", "xmlNodePtr_in", "userdata", "xmlChar_ptr" ];
+   "xmlParserCtxtPtr", "xmlDocPtr", "filepath", "fileoutput",
+   "xmlNodePtr", "xmlNodePtr_in", "userdata", "xmlChar_ptr",
+   "xmlTextWriterPtr" ];
 
 def is_known_param_type(name):
     for type in known_param_types:
@@ -369,6 +370,15 @@
 static void des_xmlNodePtr_in(int no ATTRIBUTE_UNUSED, xmlNodePtr val ATTRIBUTE_UNUSED) {
 }
 
+#define gen_nb_xmlTextWriterPtr 2
+static xmlTextWriterPtr gen_xmlTextWriterPtr(int no) {
+    if (no == 0) return(xmlNewTextWriterFilename("test.out", 0));
+    return(NULL);
+}
+static void des_xmlTextWriterPtr(int no ATTRIBUTE_UNUSED, xmlTextWriterPtr val) {
+    if (val != NULL) xmlFreeTextWriter(val);
+}
+
 """);
 
 #