Improved keyboard library

I'm hoping to try porting frotz to the playdate, and for something so heavily keyboard focused the built in keyboard isn't going to cut it. With this in mind I started making a more ergonomic text entry system, heavily inspired by the keyboard used in the GBA frotz port. It behaves like a chorded keyboard with multiple button presses combining to type one letter. A and B select the active section of the keyboard, and then the arrow keys work to select a letter within that section. You can also use the arrow keys to move the cursor within the text field to go back and edit a line. I have it all working well enough already, but there's some further polishing I want to do to make it feel better.

Bonus points if anyone knows what game this is the opening to.

Once I get things tuned up to my liking I'll probably put it up on GitHub.