Add g/G/C-o keybinds

[funnyboy-roks]

Adds the following keybinds:

• g to scroll to the top of a list/entry
• G to scroll to the bottom of a list/entry
• C-o after scrolling to return to the point that the reader was at before using g/G
  • I'm not 100% sure this is the best keybind for this operation. C-o is the default in VIM, but most other commands don't use Ctrl. Thoughts are welcome :)

[ckampfe]

Hey, I'm open to adding g and G, but I'm less keen on keeping scroll state and returning to it. If you want to remove that part, I'll accept the patch.