feat: add ctrl-a to ctrl-z to key enums

[chyroc]

Please open an issue and discuss changes before spending time on them, unless the change is trivial or an issue already exists.

[chyroc]

hi, thanks for you terminal input read repo.

i found some feat need to add to this repo.

i try to check if input is ctrl + a , i try to use e.Ctrl() && e.Rune() == 'a', but e.Ctrl() is not true, and i fail.

i try to print ctrl a to ctrl z, i found it is 1 to 26, so i create this pr.

thanks for your review my pr.

thanks

[chyroc]

@tj can you take some minutes to review my pr, thanks.

[tj]

ahh yea the "control characters" already have names & constants, so I'm not sure about adding more.

We could detect if those are pressed and add ModCtrl and populate the rune so Rune() returns what you'd expect, as well as Ctrl(), if that makes sense.

If you run man ascii in the terminal you should see the list, we should be able to just add 140 to the control character's numeric value to get the lowercase letter character

[chyroc]

hi, i click ctrl a, but ,.Ctrl() is not true, so i do this pr, to fix this