Revert "Use a different Date data type"

This reverts commit 857c7d3972.

src/xmpp/xmpp_component.hpp

@@ -6,7 +6,6 @@
 #include <network/tcp_client_socket_handler.hpp>
 #include <database/database.hpp>
 #include <xmpp/xmpp_parser.hpp>
-#include <utils/datetime.hpp>
 #include <xmpp/body.hpp>
 
 #include <unordered_map>
@@ -142,7 +141,7 @@ public:
    * Send a message, with a <delay/> element, part of a MUC history
    */
   void send_history_message(const std::string& muc_name, const std::string& nick, const std::string& body,
-                            const std::string& jid_to, const DateTime& timestamp);
+                            const std::string& jid_to, Database::time_point::rep timestamp);
 #endif
   /**
    * Send an unavailable presence for this nick