Add Silksheet(891) to item_db
Modify NPC Lora Tay to accept silk sheets (010-2)
Add NPC Hetchel(376) to 021-1
replaced wrong "cocoon" by "sheet" in sheet dialog
Allowed to buy multiple sheets, Dialogs improvement.
minor error corrections (see comments)
fixed dbl quote issues
Hetchel dialog: typo fix
Update submodule pointer for commits related to the addition of Hetchel.