Improve shadow filters (#12195)

* Rewrite shadow filtering for the new distortion
* Calculate penumbra radius using a single sample
* Avoid peter-panning effect due to filtering of short shadows
* Add adaptive filter quality for soft shadows
* Avoid sharp shadows on surfaces without normals (e.g. plants)
* Increase default and maximum soft shadow radius
* Make line numbers in shader errors match the code

src/client/clientmap.cpp

@@ -489,6 +489,8 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
 				// Do not enable filter on shadow texture to avoid visual artifacts
 				// with colored shadows.
 				// Filtering is done in shader code anyway
+				layer.BilinearFilter = false;
+				layer.AnisotropicFilter = false;
 				layer.TrilinearFilter = false;
 			}
 			driver->setMaterial(material);