Improve XEP-0308 compliance

Disallow correcting historical MUC messages, as the XEP-308 requires.

Previous changes introduce problem with
"Illicit LMC attempt from conference@server/user for message from user"

During investigation it was revealed that XEP does not recommend support
of historical MUC messages correction.

```
When used in a Multi-User Chat (XEP-0045) context,
corrections must not be allowed (by the receiver)
for messages received before the sender joined the room -
particularly a full JID leaving the room
then rejoining and correcting a message SHOULD be disallowed,
as the entity behind the full JID in the MUC may have changed.
```
https://xmpp.org/extensions/xep-0308.html#rules

Mentioned by @jubalh
Bug discovered by @jaeckel

src/ui/mucwin.c

@@ -363,7 +363,7 @@ mucwin_nick_change(ProfMucWin* mucwin, const char* const nick)
 }
 
 void
-mucwin_history(ProfMucWin* mucwin, const ProfMessage* const message)
+mucwin_history(ProfMucWin* mucwin, ProfMessage* const message)
 {
     assert(mucwin != NULL);
 
@@ -372,6 +372,9 @@ mucwin_history(ProfMucWin* mucwin, const ProfMessage* const message)
     GSList* mentions = get_mentions(prefs_get_boolean(PREF_NOTIFY_MENTION_WHOLE_WORD), prefs_get_boolean(PREF_NOTIFY_MENTION_CASE_SENSITIVE), message->plain, mynick);
     GList* triggers = prefs_message_get_triggers(message->plain);
 
+    // XEP-0308 states: `corrections must not be allowed (by the receiver) for messages received before the sender joined the room`
+    message->replace_id = NULL;
+
     mucwin_incoming_msg(mucwin, message, mentions, triggers, FALSE);
 
     g_slist_free(mentions);

src/ui/ui.h

@@ -162,7 +162,7 @@ void mucwin_occupant_affiliation_change(ProfMucWin* mucwin, const char* const ni
 void mucwin_occupant_role_and_affiliation_change(ProfMucWin* mucwin, const char* const nick,
                                                  const char* const role, const char* const affiliation, const char* const actor, const char* const reason);
 void mucwin_roster(ProfMucWin* mucwin, GList* occupants, const char* const presence);
-void mucwin_history(ProfMucWin* mucwin, const ProfMessage* const message);
+void mucwin_history(ProfMucWin* mucwin, ProfMessage* const message);
 void mucwin_outgoing_msg(ProfMucWin* mucwin, const char* const message, const char* const id, prof_enc_t enc_mode, const char* const replace_id);
 void mucwin_incoming_msg(ProfMucWin* mucwin, const ProfMessage* const message, GSList* mentions, GList* triggers, gboolean filter_reflection);
 void mucwin_subject(ProfMucWin* mucwin, const char* const nick, const char* const subject);

tests/unittests/ui/stub_ui.c

@@ -363,7 +363,7 @@ mucwin_roster(ProfMucWin* mucwin, GList* occupants, const char* const presence)
 {
 }
 void
-mucwin_history(ProfMucWin* mucwin, const ProfMessage* const message)
+mucwin_history(ProfMucWin* mucwin, ProfMessage* const message)
 {
 }
 void