Rename b/lines to b/line-count
Unify scroll-{up,down}-half-page
Refactor b/scroll-half-page
Add :pre for move-to-line
Rename scroll-half-page -> move-and-scroll-half-page
Rename with-cursor -> move-cursor
Compose key handler functions up front
Introduce defhandler macro
Extract avi.keymap
Make handler names stable