Allow traversing directionally after bidirectional search

[tvdab]

When doing a bidirectional search, the next_target and prev_target keybindings doesn't work. I would love if next_target would jump to the next match in the direction of the end of the buffer and prev_target would jump in the other direction.

[ggandor]

You can use repeat keys (:h leap-repeat), which effectively do the same.

To make traversal mode work for non-directional motions, we should maintain additional tables (winlocal-directional-idx : original-idx) for each window, I'm not sure it would worth the effort. But I will give it some thought.

[ggandor]

Related #136.

[tvdab]

Thx for your fast reply. It seems to work :)