Add null values for options, new syntax for /set, reintroduce temporary IRC server feature, improve IRC server options, new functions in API

src/plugins/scripts/script-api.c

@@ -347,6 +347,7 @@ script_api_config_new_option (struct t_weechat_plugin *weechat_plugin,
                               int min, int max,
                               const char *default_value,
                               const char *value,
+                              int null_value_allowed,
                               void (*callback_check_value)(void *data,
                                                            struct t_config_option *option,
                                                            const char *value),
@@ -416,6 +417,7 @@ script_api_config_new_option (struct t_weechat_plugin *weechat_plugin,
     new_option = weechat_config_new_option (config_file, section, name, type,
                                             description, string_values, min,
                                             max, default_value, value,
+                                            null_value_allowed,
                                             callback1, new_script_callback1,
                                             callback2, new_script_callback2,
                                             callback3, new_script_callback3);

src/plugins/scripts/script-api.h

@@ -68,6 +68,7 @@ extern struct t_config_option *script_api_config_new_option (struct t_weechat_pl
                                                              int min, int max,
                                                              const char *default_value,
                                                              const char *value,
+                                                             int null_value_allowed,
                                                              void (*callback_check_value)(void *data,
                                                                                           struct t_config_option *option,
                                                                                           const char *value),