add `i` to enter and `o` to exit dir

[ericd23]

While navigating directories using the hjkl, Enter and Backspace is relatively distant. I added alternative keybindings: i for entering a directory ("in") and o for exiting a directory ("out"), which are closer to the hjkl and easy to remember.

[antonmedv]

Nice idea. What i & o used in vim and emacs usually for?

[ericd23]

In Vim, i is for entering "insert" mode. o creates an empty line under cursor and enters "insert" mode. In Emacs, i and o insert the actual letters.

I was also thinking something like n (next) for entering and p (previous) for exiting, which is also quite ergonomic.

[tuzu128]

I would change it from i and o to h and l.