feat(core): Ensure that all actions are compared to fixed point in time (#1236) (#1458)

i.e. world update start

src/server/game/Server/WorldSocket.cpp

@@ -25,6 +25,7 @@
 #include "ByteBuffer.h"
 #include "Opcodes.h"
 #include "DatabaseEnv.h"
+#include "GameTime.h"
 #include "BigNumber.h"
 #include "SHA1.h"
 #include "WorldSession.h"
@@ -839,7 +840,7 @@ int WorldSocket::HandleAuthSession(WorldPacket& recvPacket)
     //! Negative mutetime indicates amount of seconds to be muted effective on next login - which is now.
     if (mutetime < 0)
     {
-        mutetime = time(NULL) + llabs(mutetime);
+        mutetime = GameTime::GetGameTime() + llabs(mutetime);
 
         PreparedStatement* stmt = LoginDatabase.GetPreparedStatement(LOGIN_UPD_MUTE_TIME_LOGIN);