Allow the user to provide some sort of input

[fritzrehde]

My design idea would be to add a possible subcommand:
read -- exec <blocking|non-blocking> ...
So the user input would be read inside the TUI, saved into a env variable (maybe INPUT), which is then set in the subprocess where the exec command is set.
This would make watchbind a lot more reactive and customizable.

[fritzrehde]

Actually, it makes more sense to allow a TUI to have custom internal state. So the logical syntax for reading user input into a variable would be:

read-into NAME

and then $NAME will be set both in the watched command and all subcommands as a environment variable.
Additionally, we would allow users to specify state like so:

set-state NAME -- <cmd>
unset-state NAME

where the output of <cmd> gets saved in the state.

[fritzrehde]

The only thing missing now is the ability to allow the user to set some state dynamically, i.e. by inputting some text into a text field. This is being worked on.