Positive Z-levels(WIP)

Since I want to add a second floor to the Rivtech facility, I need to get positive Z-levels working, since a lot of the base is already there.

After diving into the code(including that huge if statement in mapgen.cpp), I *think*, I know what needs to be done to get it working.
Merge branch 'master' of https://github.com/CleverRaven/Cataclysm-DDA into positive-z-levels
Added sky terrain, sky overmap
Finished up, everything seems to work, as I want.
Added 3-D version of Motel
Added 3-D version of Office Tower(empty) thanks to acidia
Merge branch 'master' of https://github.com/CleverRaven/Cataclysm-DDA into positive-z-levels
Changed t_sky to t_open_air and changed the colours on them to make them more managable.
Fixed automap issue-apparently know up and know down are bad...
Transfered 3-D Buildings and made a mod.  Players will not be able to access new z-levels unless they use the debugger.
Reverted buildings back to their orignal settings.
Merge pull request #1 from CleverRaven/master

Update
Update for evac center
Added Evac Center
Added Evac Merchant and Guard Text
Added Evac Center
Added support for Evac shopkeeper
Added Evac Center
Added Placespecial NPC support
Added guard, hostile_guard, and evac_merchant support
added place_npc support