Command history proposal

[hermes-diactoros]

As said in #81, this is a preliminary command history proposal. It attempts to be as well-behaved as possible.

There's a command history array, an index pointing at the current item in the history (-1 if a new command has been executed), and a command buffer holding whatever is in the input box, so that no stuff is lost while browsing through previous commands.

I have tested most edge cases, but there might be bugs!

(sorry about the extra spaces on empty lines getting removed, my text editor did that automatically)

EDIT1: I could certainly define some local variables in order to avoid long references to "r.operator.cmd_history..." and so on.

[neauoire]

Let's try this out 👍

[eelfroth]

really cool feature! one little problem with this: when you are editing multiline-messages, you can't use up/down anymore to navigate to different lines in the same command