#126 Housing: restrict housing to city zones only

DB zones table has city_zone column available, but no zones are setup properly. Need this populated before restricting housing to the proper zones.

city_zone apparently is part of LoadSpecialZones() ... since we already have always_loaded in there, which is what sets a zone to load on startup, city_zone shall be re-purposed in the future to identify city-based zones... there is no other use-case for them currently since all zones entry has city_zone=0.

Need some area based support for docks also..

The new, fast and easy way uses the Housing & Leaderboards window. If you are in any major city, you can access any house your character owns by:

    Pressing C to open the Character window.
    Click on the side-tab for Housing to view the list of your houses.
    Choose the house on the list and hit Access. This will open the Housing and Leaderboards window.
    If the house is one without any upkeep costs, you'll instantly enter it. 

    The cities you can do this from are The City of Freeport, The City of Qeynos, Neriak, Kelethin, Gorowyn, or New Halas. 

        This can also be done from the docks of The Commonlands and Antonica