changing the way the .c is generated, extending the tests coverage fixing

* gentest.py testapi.c: changing the way the .c is generated,
  extending the tests coverage
* include/libxml/nanoftp.h nanoftp.c elfgcchack.h doc/*: fixing some
  function signatures, regenerating stuff
* SAX2.c parser.c xmlIO.c: another set of bug fixes and API hardening
Daniel
diff --git a/nanoftp.c b/nanoftp.c
index 0002226..5870936 100644
--- a/nanoftp.c
+++ b/nanoftp.c
@@ -1471,7 +1471,7 @@
  */
 
 int
-xmlNanoFTPCwd(void *ctx, char *directory) {
+xmlNanoFTPCwd(void *ctx, const char *directory) {
     xmlNanoFTPCtxtPtr ctxt = (xmlNanoFTPCtxtPtr) ctx;
     char buf[400];
     int len;
@@ -1517,7 +1517,7 @@
  */
 
 int
-xmlNanoFTPDele(void *ctx, char *file) {
+xmlNanoFTPDele(void *ctx, const char *file) {
     xmlNanoFTPCtxtPtr ctxt = (xmlNanoFTPCtxtPtr) ctx;
     char buf[400];
     int len;
@@ -1913,7 +1913,7 @@
 
 int
 xmlNanoFTPList(void *ctx, ftpListCallback callback, void *userData,
-	       char *filename) {
+	       const char *filename) {
     xmlNanoFTPCtxtPtr ctxt = (xmlNanoFTPCtxtPtr) ctx;
     char buf[4096 + 1];
     int len, res;