Used by the routine at UPDATE_KNIGHT.

The end of most handlers (through REDRAW_ACTOR). Sets up the draw at the record's position through SETUP_SPRITE_DRAW, and in the other register bank the erase at the position saved in the workspace through SETUP_ERASE; then ALIGN_ROWS compares the two y positions, erases (or draws) the rows the old and new pictures do not share, and hands the rest to ERASE_DRAW_ROWS, so each screen row is rubbed out and redrawn close together.