Script Engine Update Phase 2

Fixed constant '\'' support (e.g. Monster's_Feed now works), made possible thanks to Haruna!
Ducked some debug messages in set_reg
- Script Engine Update: Phase 2, New Universal Shop Format
-- 4 new script commands (documentation will follow after test phase is complete)
--- openshop()
--- sellitem(...)
--- stopselling(...)
--- setcurrency(...)
-- new shops are fully able to be controlled by 'script' npc types, a new 'trader' npc subtype is available however which functions just like a 'script' type with the exception that clicking on 'trader' npc types automatically launches the shop as opposed to running the script from the start (shops under a 'script' type must use openshop() instead)
-- The shops powered by this feature have 5 unique currency types which can be adjusted with setcurrency, each shop can have up to 2 concurrent currencies (official behavior for cashshop npc types), default currency is zeny and, again, can be modified with setcurrency, available types are:
--- ZENY, CHAR_VAR (charreg), ACC_VAR (accreg), INSTANCE_VAR (instance-sub-mapreg), ITEM (item id/name)
-- check npc/merchants/shops.txt for a glimpse of the new design (Made Possible Thanks to Yommy!)
-- Design by Yommy, jaBote, mkbu95, Gepard and Emistry.

Signed-off-by: shennetsind <ind@henn.et>