Missing keyboard modifiers and symbols

[RaphGL]

The mouse parser is complete but the keyboard is missing modifier detection for single byte inputs.

[RaphGL]

I no longer remember what is missing to be honest. I think the vast majority or all of the ctrl and shift modifiers have been implemented.

But I know for a fact that the Alt modifiers cannot be detected.
Here's a nice table for the expected inputs:
https://gist.github.com/jonlabelle/7a76ecd29976aeb30877be326c683979#list-of-keyboard-strings

[RaphGL]

Alt keys are now handled but on kitty numpad does not simply return the numbers so alt detection is not working with it. This needs investingating

[RaphGL]

I've noticed that on linux TTY the function keys aren't being properly detected either