Commit Briefs
fix the scroll commands
forward_line(buffer, body_lines) is not a real scrolling. We need to move the top_line to have a nice effect.
wrap the minibuffer check in a macro
and while there improve the error message.
refactor struct vline
the new `meta.data' field will be useful for holding completions data.
improve history navigation messages
"no prev item" (or next) can be misleading during a completing-read