linenoise: renumber history indices in undo items

This has to be done because each time a history line is added,
or taken back, the relative numbers change.

* linenoise/linenoise.c (undo_pop): New static function.
(restore_undo): Skip undo items which refer to lines of
history which no longer exist. Restore history[0] also.
(renumber_undo_hist): New static function.
(edit): When leaving, and removing the extra history
line representing the current line, renumber the undo
items by -1.
(lino_hist_add): After adding a line, bump the undo item
history indices by 1.

0 files changed, 0 insertions, 0 deletions