'h' and 'l' move the cursor by "modifier" characters. 'j' and
'k', by lines.

'H' goes to the beginning of the line, 'L' to the end.

'w' moves forward by "modifier" words. 'b' moves backward.
'W' moves to end-of-word. 'B', backwards.

'I', 'F', 'X' and 'E' invoke the corresponding command from the
Block Editor (B100). Refer to documentation there.

'o' inserts a blank line after the cursor. 'O', before.

'D' deletes "modifier" lines at the cursor.

                                                        (cont.)
