`ixyz<Esc>` leaves the cursor on `z``ixyz<Esc>` leaves the cursor on `z`
Remove unused `last-explicit-j`
Introduce avi.string ns
Rename `line` to `string`
Simplify `modify-line`, rename to `update-line`
Extract `splicev`
Use `splicev` in `delete-current-line`
`backspace` uses `update-line`
Simplify `b/backspace`
`ix<Enter>` inserts a new line`insert-text` uses `splicev`
Extract `splice`
Make splice work on vectors, kill splicev