remove implication sheet_grab -> bed_sheet
Bed sheet is supposed to be for when a bed sheet is visible but not the entire bed. Think dakimakura backgrounds. According to the bed wiki, bed sheet is supposed to be mutually exclusive with bed. I rewrote the bed sheet wiki just now to make this explicit.
As such, sheet grab shouldn't imply bed sheet because it conflicts with bed.
EDIT: The bulk update request #1878 (forum #152758) has been approved by @Type-kun.
Updated by DanbooruBot