The first stable release of Ion.

If we want to go more fancy, we could use kalk as builtin and call it within $(math expression) as trait object.

Overall goal enforce readability in scripts + maintenability + REPL editing support (+ editor tooling) => regex + syntax checking in a loop for editing: How to archive this at best without exploding complexity?

REPL improvements (for zoxide support and proper starship support):

1. must differentiate between status line, cursor symbol and cursor field.

2. ideally REPL can properly handle background processes with counters, so one does not need ugly hacks. (Background processes are currently broken.)

3. Aliased functions (of the initrc and other sourced files) must start with capital letters, if they are needed (I am not convinced yet).