Bind UP to action_up

Implement C-u and C-d

Implement action_top

(mostly) fix scrolling up from EOF

most: implement scrolling up

This only works on seekable files. TODO: Implement read caching overlay
stream which makes non-seekable streams seekable by stashing reads in
memory.

Add more scroll down bindings

Implement scrolling down

refactor line drawing and add configuration

reorder state struct

Draw ellipsis at end of long lines

Initial commit