command_line_changed:
- Check (current_SID == 0) instead of KeyTyped
- We want to update during mappings (KeyTyped is false then).
- Check vpeekc_any()
- Avoids unnecessary work.
- Avoids triggering live preview during macros.
- Caveat: This makes the redraw "stutter" if user spams (holds a key)
in the replace pattern. But that scenario is not important.
- Update screen if the command is changed to a non-live command.
(`s->live` goes from true => false) => clears the preview
command_line_execute:
- Let CTRL-C cancel live preview
do_sub:
- Enforce a time limit ('redrawtime').
- Unset 'inccommand' if time limit is reached.
Closes#5602Closes#5585