[Rule] Allow GMs to silently summon (#3910)

* [Rule] Allow GMs to silently summon

Disable to silently summon players with #summon.

Converted SummonPC to a MessageString

* Implementing an automatic detection of gm hidden mode and silent summoning.

zone/gm_commands/summon.cpp

@@ -91,7 +91,7 @@ void command_summon(Client *c, const Seperator *sep)
 			c->GetZ(),
 			c->GetHeading(),
 			2,
-			GMSummon
+			c->GetHideMe() ? GMHiddenSummon : GMSummon
 		);
 		return;
 	}