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).
Introducing BRPQ rewarding system (KPQ/LPQ clear-like) and patched
issues regarding "no apparent party leader" after party leader
disconnects and reconnects.
