Room graphical fixes/improvements.

-Added new archway textures without graphical errors (grd02703.bgf, grd02704.bgf).
-Fixed archway in NBQ, fixed sidedef errors around arch.
-Fixed archway in SBQ and sidedef errors around arch.
-Fixed missing line on Ivory Chapel in Cor Noth.
-Fixed archway at MG CN (g4.roo).
-Fixed archway in East Ende/Outskirts (i6.roo); took wreath ID tag off Konima's guildhall entrance.
-Fix graphical error near entrance to CN from King's Way (g5.roo).
-Fix archways in Den of Shadows.
-Show snow through windows in Abandoned Warehouse guild hall.
-Fix sidedefs with incorrectly tagged IDs for snow in FoF guild hall.
-Added snow/ice in Hall of Slaughtered Command.
-Added snow to outside section of Barking Monster tavern.
-Added tags to the water sector and sidedefs in Fields to change texture appropriately.
-Tagged water outside BQ adv hall window for ice.
-Fix missing sidedef in Dungeon of Castle Brax (lichmaze.roo).
-Fixed snow/ice in meeting place of the Gods.
-Raised ceiling height in Marion and Tos.