Feature request: Add support for more navigation keys

[loserMcloser]

• KP_Enter should have the same function as Return.
• Right (and KP_Right) to expand a directory, Left (and KP_Left) to collapse a directory.
• There should be a shortcut key to toggle keyboard focus between the directory tree and the preview pane so that when the keyboard focus is on the preview pane, the arrow keys and page up/down can be used to scroll in the previewed file, instead of only being able to scroll with the mouse.

[juftin]

Oh nice, most of these seem super easy. FWIW, the tab key works pretty well to toggle between the directory and preview pane and the arrow keys work as expected when you switch like this. I'll look into the KP_ keys