The shadow Rendering on terrain should be part of WED, as the Light/shadow Rendering on blocks
is at the moment. This is totally the same concept: Create static lightning onto
the unmovable Structures of your level. The terrain could get a flag in WED: "light rendering"
and WED alters the skin of the terrain and applies the shadowmap onto it, reqacting on
the sun and Lightsources of the level.

This is a "soft shadow" then, but baked onto the terrain.