Add exit sequence

[donno2048]

as suggested in #127

[donno2048]

Used ctrl+alt+end however, as it even less likely to be used in emulation (some software accepts ctrl+end as go to end of document)

[dmsc]

Hi!

I like being able to exit the emulator with a key press - but this currently only work if the emulated program reads the keyboard - if it is inside a busy loop it won't work.

As always, the best way to terminate the emulator is simply to close the terminal window 😝

Have Fun!

[donno2048]

Hi!

I like being able to exit the emulator with a key press - but this currently only work if the emulated program reads the keyboard - if it is inside a busy loop it won't work.

The emulator enters the update_keyboard method every iteration of the main loop so this works if #135 is merged

Will wait to see if it will...