Clear CommandQueue after failing all remaining commands

This prevents the query from waiting indefinitely in CommandQueue#quit

Author: rogermb

src/main/java/com/github/theholywaffle/teamspeak3/CommandQueue.java

@@ -222,6 +222,9 @@ void failRemainingCommands() {
 			for (Command command : allCommands) {
 				command.getFuture().fail(new TS3QueryShutDownException());
 			}
+
+			sendQueue.clear();
+			receiveQueue.clear();
 		} finally {
 			queueLock.unlock();
 		}