core: add pointer in some callbacks (closes #406)

This pointer is the first argument received by callbacks, and the
existing argument "data" is now automatically freed by WeeChat when the
object containing the callback is removed.

With this new pointer, the linked list of callbacks in scripts has been
removed. This will improve speed of scripts (using a lot of hooks),
reduce memory used by scripts and reduce time to unload scripts.

Following functions are affected in the C API:

* exec_on_files
* config_new
* config_new_section
* config_new_option
* hook_command
* hook_command_run
* hook_timer
* hook_fd
* hook_process
* hook_process_hashtable
* hook_connect
* hook_print
* hook_signal
* hook_hsignal
* hook_config
* hook_completion
* hook_modifier
* hook_info
* hook_info_hashtable
* hook_infolist
* hook_hdata
* hook_focus
* unhook_all_plugin
* buffer_new
* bar_item_new
* upgrade_new
* upgrade_read

src/plugins/script/script-repo.c

@@ -1140,11 +1140,11 @@ script_repo_file_read (int quiet)
 
     if (!script_repo_max_length_field)
     {
-        script_repo_max_length_field = weechat_hashtable_new (32,
-                                                              WEECHAT_HASHTABLE_STRING,
-                                                              WEECHAT_HASHTABLE_INTEGER,
-                                                              NULL,
-                                                              NULL);
+        script_repo_max_length_field = weechat_hashtable_new (
+            32,
+            WEECHAT_HASHTABLE_STRING,
+            WEECHAT_HASHTABLE_INTEGER,
+            NULL, NULL);
     }
     else
         weechat_hashtable_remove_all (script_repo_max_length_field);
@@ -1201,8 +1201,7 @@ script_repo_file_read (int quiet)
     descriptions = weechat_hashtable_new (32,
                                           WEECHAT_HASHTABLE_STRING,
                                           WEECHAT_HASHTABLE_STRING,
-                                          NULL,
-                                          NULL);
+                                          NULL, NULL);
 
     /* read plugins.xml.gz */
     while (!gzeof (file))
@@ -1422,17 +1421,19 @@ script_repo_file_read (int quiet)
  */
 
 int
-script_repo_file_update_process_cb (void *data, const char *command,
+script_repo_file_update_process_cb (const void *pointer, void *data,
+                                    const char *command,
                                     int return_code, const char *out,
                                     const char *err)
 {
     int quiet;
 
     /* make C compiler happy */
+    (void) data;
     (void) command;
     (void) out;
 
-    quiet = (data == 0) ? 0 : 1;
+    quiet = (pointer) ? 1 : 0;
 
     if (return_code >= 0)
     {
@@ -1479,8 +1480,7 @@ script_repo_file_update (int quiet)
     options = weechat_hashtable_new (32,
                                      WEECHAT_HASHTABLE_STRING,
                                      WEECHAT_HASHTABLE_STRING,
-                                     NULL,
-                                     NULL);
+                                     NULL, NULL);
     if (options)
     {
         url = script_build_download_url (
@@ -1499,7 +1499,8 @@ script_repo_file_update (int quiet)
                 options,
                 weechat_config_integer (script_config_scripts_download_timeout) * 1000,
                 &script_repo_file_update_process_cb,
-                (quiet) ? (void *)1 : (void *)0);
+                (quiet) ? (void *)1 : (void *)0,
+                NULL);
             free (url);
         }
         weechat_hashtable_free (options);
@@ -1513,11 +1514,13 @@ script_repo_file_update (int quiet)
  */
 
 struct t_hdata *
-script_repo_hdata_script_cb (void *data, const char *hdata_name)
+script_repo_hdata_script_cb (const void *pointer, void *data,
+                             const char *hdata_name)
 {
     struct t_hdata *hdata;
 
     /* make C compiler happy */
+    (void) pointer;
     (void) data;
 
     hdata = weechat_hdata_new (hdata_name, "prev_script", "next_script",