improve navigation shortcuts

[slartibart70]

There are already vim-inspired navigation keys (g/G, hjkl) but not page/half-page forwards.
Esp. navigating big file trees, sth. like Ctrl-D/Ctrl-U or Ctrl-B/Ctrl-F would be handy.
Any chance to see this implemented?

[deveshctl]

Thanks for the suggestion! This is a great fit for layerx. Page and half page scrolling would make navigating large file tree much smoother, and it lines up nicely with the Vim-inspired keys already in place. I'll look into adding it.