This change adds support for choosing a pane based on direction; and
adds default keybindings (`cmd+k cmd+{left,right,up,down}`) and vim
keybindings.
Release Notes:
- Add support for navigating to the next pane in a given direction using
`cmd+k cmd-{up,down,left,right}`
([#476](https://github.com/zed-industries/community/issues/476),
[#478](https://github.com/zed-industries/community/issues/478))
- Vim: adds support for many window related shortcuts: `ctrl-w
{h,j,k,l,up,down,left,right,w,W,p}` for navigating around panes, `ctrl-w
{q,c}` for closing panes and `ctrl-w {v,s}` for splitting panes.