Abstracted XML parser library and switched to autotools building.

expat is still the default parser, but libxml2 can also be used
via an option to the configure script.  New parsers can easily be
added by implementing a parser_foo.c that uses the interface defined
in parser.h.

src/common.h

@@ -31,8 +31,7 @@
 #include "tls.h"
 #include "hash.h"
 #include "util.h"
-
-#include "expat.h"
+#include "parser.h"
 
 /** run-time context **/
 
@@ -167,6 +166,7 @@ struct _xmpp_conn_t {
     int tls_failed; /* set when tls fails, so we don't try again */
     int sasl_support; /* if true, field is a bitfield of supported 
 			 mechanisms */ 
+    int secured; /* set when stream is secured with TLS */
 
     /* if server returns <bind/> or <session/> we must do them */
     int bind_required;
@@ -189,9 +189,7 @@ struct _xmpp_conn_t {
 
     /* xml parser */
     int reset_parser;
-    XML_Parser parser;
-    int depth;
-    xmpp_stanza_t *stanza;
+    parser_t *parser;
 
     /* timeouts */
     unsigned int connect_timeout;
@@ -217,6 +215,8 @@ struct _xmpp_conn_t {
 void conn_disconnect(xmpp_conn_t * const conn);
 void conn_disconnect_clean(xmpp_conn_t * const conn);
 void conn_open_stream(xmpp_conn_t * const conn);
+void conn_prepare_reset(xmpp_conn_t * const conn, xmpp_open_handler handler);
+void conn_parser_reset(xmpp_conn_t * const conn);
 
 
 typedef enum {
@@ -241,19 +241,6 @@ struct _xmpp_stanza_t {
     hash_t *attributes;
 };
 
-int xmpp_stanza_set_attributes(xmpp_stanza_t * const  stanza,
-			       const char * const * const attr);
-
-/* parser functions */
-void parser_handle_start(void *userdata,
-			 const XML_Char *name,
-			 const XML_Char **attr);
-void parser_handle_character(void *userdata, const XML_Char *s, int len);
-void parser_handle_end(void *userdata, const XML_Char *name);
-void parser_prepare_reset(xmpp_conn_t * const conn, 
-			  xmpp_open_handler handler);
-int parser_reset(xmpp_conn_t * const conn);
-
 /* handler management */
 void handler_fire_stanza(xmpp_conn_t * const conn,
 			 xmpp_stanza_t * const stanza);