When Tab in the cmdline completes to more than one candidate,
show a popup above the cmdline listing the candidates. Standard
shell completion behaviour (fish, zsh, bash). Helps users pick
the right file when many match.
- Cmdline::completions: Vec<String> field stores the candidates
- Cmdline::clear_completions() for cleanup on commit/cancel
- Cmdline::has_completions() returns true if >1 candidates
- Cmdline::render shows the popup when has_completions() is true
- Esc/Enter in handle_key clears completions
Added 1 unit test verifying completions are populated and
clear_completions works.
Tests: 1402 pass (was 1401), zero warnings.
vasilito
dece1210c7