Add parity in REST /world/meteor with /dropmeteor functionality

See #1361

It looks like we're setting spawnMeteor before executing WorldGen.dropMeteor()
in the command but not in the REST API. This makes the two code paths
behave the same.

TShockAPI/Rest/RestManager.cs

@@ -687,6 +687,7 @@ namespace TShockAPI
 		[Token]
 		private object WorldMeteor(RestRequestArgs args)
 		{
+			WorldGen.spawnMeteor = false;
 			WorldGen.dropMeteor();
 			return RestResponse("Meteor has been spawned");
 		}