Changed map chair bonus healing mechanic to be a player skill, instead of promptly available for all players (healing buff takes place only if the player has the skill). Hired Merchant now properly checks for a space on the inventory before permitting a player to buy an item/bundle. Minor fix with concurrency on MapleStorage.
Added mechanics for the EXP/DROP cash coupons (such as enabling
out-of-time active coupons via command and automatic update of active
ones over the designed interval). Created MapleCouponInstaller as means
to gather info about the coupon intervals and rates from the WZs (the
generated SQL table is already updated on the db_database.sql file).
