Implement a previous client command stack and Up and Down key access

[Rythious]

Now that I'm getting into testing through the client window, I'm sorely missing the ability to hit the up arrow on my keyboard and have it enter my previous command. Mimic the behavior that a console window allows and keep a stack of the previously entered commands in the client. Then bind the up arrow key and down arrow key to navigate this stack, populating the input text field while navigating.