Inventory Item ordering

Fixed inventory item label displays. Previously they were sometimes
being drawn behind other items. This still happens, but much less
frequently.
NPC Walking/minor fixes

NPC walking is handled. CanWalk method for characters updated to match
eoserv. Fixed map rendering - discovered that there was a sentinal value
for tile graphics that basically means "do not render anything here".
NPC Walk Fixes/Chat Bubbles

NPC walking is a little better. NPC and Player chat now shows in chat
bubbles, and NPC chat shows in the chat tab.
Map Renderer Improvements

Mouse Cursor for map renderer, picking up items from map, names over map
entities when the mouse is over them.
Item drop and pickup

Adding ability to pick items up off the map and drag/drop them on the
map