ignore "decorated" chunks

This seems to fix lighting problems by ignoring chunks with no lighting (wiki suggests that "decorating" happens before "lighting")

overviewer_core/world.py

@@ -759,7 +759,7 @@ def get_chunk(self, x, z):
         # Empty is self-explanatory, and liquid_carved and carved seem to correspond
         # to SkyLight not being calculated, which results in mostly-black chunks,
         # so we'll just pretend they aren't there.
-        if chunk_data['Status'] in ("empty", "carved", "liquid_carved"):
+        if chunk_data['Status'] in ("empty", "carved", "liquid_carved", "decorated"):
             raise ChunkDoesntExist("Chunk %s,%s doesn't exist" % (x,z))
 
         # Turn the Biomes array into a 16x16 numpy array