world editor: objects falling trough the floor

[jalmasi]

... and it's not a bug, but a feature! ;)

WorldeEditor.alignObject() casts a ray down, then puts the object there. Simple, assuming that bottom of the object is at y=0. But if bottom is below y=0, the object 'falls through' the ground or whatever is below. This method needs to account for object geometry, e.g. bounding box minimum.