Add storeroom to vendor configuration

Vendors now have a storeroom parameter.  If the vendor has a
storeroom, it will use the contents of the room instead of its
inventory for the items to be sold.

This was done primarily so consigment shops could specify a house room
as a storeroom so that objects could be automatically saved.
Consignment added to vendor

Two commands, consign and unconsign were added to the vendor.  A
consignor and consign_price were added to the obj_data structure.
same_obj() was modified so that items with different consignors are
considered different.
Improve logging of consignment activities
Merge pull request #253 from dlowe-net/feature-vendor-consignment

Feature vendor consignment
Fix crash bug in logging and redirect consignments to vendor log
Merge pull request #254 from dlowe-net/fix-vendor-logging

Fix crash bug in logging and redirect consignments to vendor log
Save storeroom houses and characters after vendor transactions
Merge pull request #255 from dlowe-net/feature-vendor-saving

Save storeroom houses and characters after vendor transactions
Fix vendor selling calculation
Fix tattooist special breakage from function signature change
Merge pull request #256 from dlowe-net/fix-vendor-sell-value

Fix vendor sell value