Parse mentions and triggers in muc history if display is 'regular'

Fix https://github.com/profanity-im/profanity/issues/1261

tests/unittests/xmpp/stub_xmpp.c

@@ -131,7 +131,7 @@ void message_send_gone(const char * const barejid) {}
 void message_send_invite(const char * const room, const char * const contact,
     const char * const reason) {}
 
-bool message_is_sent_by_us(ProfMessage *message, bool checkOID) {
+bool message_is_sent_by_us(const ProfMessage *const message, bool checkOID) {
     return TRUE;
 }