[server.jar] Command input is broken up if chat is being spammed by commands/chat.

If players are typing in chat it is impossible for the server owner to type commands in the cmd prompt. This happens too when their is a clock of commands used.

Example: if their is a clock of giving everyone the saturation effect, the server owner will not be able to save his server before stopping. It's impossible for them to type save-all stop. Instead they have to click the x in the corner of the cmd prompt which is unsafe.