Add per-shop setting for the shop to not require a cost item
Add command (/ts setFree?) to change a shop into free-mode that doesn't require a cost item
This will apply to Trade and iTrade shops only(no BiTrade) and will only be effective if cost items are present for the shop(in order to use must set free-mode to enabled and not set a cost or must remove all costs)
Modify trade code to appropriately handle free-mode setting and no cost item instead of only checking for iTrade with no cost
/ts setFree
?) to change a shop into free-mode that doesn't require a cost item