MC has search history navigation in the find prompt via arrow
keys. TLC's SearchState already had a history() list but no
way to navigate it without using the Alt-/ popup.
Add history_up() / history_down() / reset_history_cursor() to
SearchState. Wire Up/Down in the Find/Replace prompt to cycle
through the history. Down past the newest entry clears the
prompt back to the live pattern.
Added 3 unit tests covering: walk backwards, walk forward with
stop signal, empty history.
Tests: 1396 pass (was 1393), zero warnings.
vasilito
f568f9cbb2