irc: search options irc.ctcp.* with lower case ctcp string

doc/de/weechat_user.de.adoc

@@ -3994,6 +3994,11 @@ folgenden Befehl:
 /set irc.ctcp.version "I'm running WeeChat $version, it rocks!"
 ----
 
+// TRANSLATION MISSING
+[NOTE]
+The name of CTCP must be in lower case. That means option _irc.ctcp.VERSION_
+would not work.
+
 Wenn Sie die Anfrage CTCP "VERSION" blockieren möchten (es wird nicht darauf
 geantwortet) dann löschen Sie einfach den Rückgabe-String:
 

doc/en/weechat_user.en.adoc

@@ -3918,6 +3918,10 @@ For example, to customize reply to CTCP "VERSION", use following command:
 /set irc.ctcp.version "I'm running WeeChat $version, it rocks!"
 ----
 
+[NOTE]
+The name of CTCP must be in lower case. That means option _irc.ctcp.VERSION_
+would not work.
+
 If you want to block CTCP "VERSION" (do not reply to a query), then set empty
 string:
 

doc/fr/weechat_user.fr.adoc

@@ -4036,6 +4036,10 @@ commande suivante :
 /set irc.ctcp.version "Je suis sous WeeChat $version, ça déchire !"
 ----
 
+[NOTE]
+Le nom du CTCP doit être en minuscules. Cela signifie que l'option
+_irc.ctcp.VERSION_ ne fonctionnerait pas.
+
 Si vous voulez bloquer le CTCP "VERSION" (ne pas répondre à une demande), alors
 affectez une chaîne vide :
 

doc/it/weechat_user.it.adoc

@@ -4227,6 +4227,11 @@ seguente comando:
 /set irc.ctcp.version "Uso WeeChat $version, fico!"
 ----
 
+// TRANSLATION MISSING
+[NOTE]
+The name of CTCP must be in lower case. That means option _irc.ctcp.VERSION_
+would not work.
+
 Se si desidera bloccare CTCP "VERSIONE" (non rispondere ad una query),
 allora basta impostare una stringa vuota:
 

doc/ja/weechat_user.ja.adoc

@@ -4081,6 +4081,11 @@ CTCP 応答をカスタマイズしたり、いくつかの CTCP
 /set irc.ctcp.version "I'm running WeeChat $version, it rocks!"
 ----
 
+// TRANSLATION MISSING
+[NOTE]
+The name of CTCP must be in lower case. That means option _irc.ctcp.VERSION_
+would not work.
+
 CTCP "VERSION" 要求をブロックする (要求に対する応答を行わない)
 には、空文字列を設定してください:
 

doc/pl/weechat_user.pl.adoc

@@ -3967,6 +3967,11 @@ pomocą polecenia:
 /set irc.ctcp.version "I'm running WeeChat $version, it rocks!"
 ----
 
+// TRANSLATION MISSING
+[NOTE]
+The name of CTCP must be in lower case. That means option _irc.ctcp.VERSION_
+would not work.
+
 Jeśli chcesz zablokować CTCP "VERSION" (nie odpowiadać na zapytanie), ustaw
 pusty ciąg:
 

doc/sr/weechat_user.sr.adoc

@@ -3706,6 +3706,11 @@ CTCP одговори могу да се прилагоде, или неки CTC
 /set irc.ctcp.version "Користим WeeChat $version, одличан је!"
 ----
 
+// TRANSLATION MISSING
+[NOTE]
+The name of CTCP must be in lower case. That means option _irc.ctcp.VERSION_
+would not work.
+
 Ако желите да блокирате CTCP „VERSION” (да се не пошаље одговор на овај упит), онда поставите празан стринг:
 
 ----

src/plugins/irc/irc-ctcp.c

@@ -79,23 +79,36 @@ const char *
 irc_ctcp_get_reply (struct t_irc_server *server, const char *ctcp)
 {
     struct t_config_option *ptr_option;
-    char option_name[512];
+    char option_name[512], *ctcp_lower;
 
-    snprintf (option_name, sizeof (option_name), "%s.%s", server->name, ctcp);
+    ctcp_lower = weechat_string_tolower (ctcp);
+    if (!ctcp_lower)
+        return NULL;
+
+    snprintf (option_name, sizeof (option_name),
+              "%s.%s", server->name, ctcp_lower);
 
     /* search for CTCP in configuration file, for server */
     ptr_option = weechat_config_search_option (irc_config_file,
                                                irc_config_section_ctcp,
                                                option_name);
     if (ptr_option)
+    {
+        free (ctcp_lower);
         return weechat_config_string (ptr_option);
+    }
 
     /* search for CTCP in configuration file */
     ptr_option = weechat_config_search_option (irc_config_file,
                                                irc_config_section_ctcp,
-                                               ctcp);
+                                               ctcp_lower);
     if (ptr_option)
+    {
+        free (ctcp_lower);
         return weechat_config_string (ptr_option);
+    }
+
+    free (ctcp_lower);
 
     /*
      * no CTCP reply found in config, then return default reply, or NULL