Improve LOD Building and Lighting speed for BigGlobe worlds

Thanks Builderb0y!

core/src/main/java/com/seibel/distanthorizons/core/dataObjects/transformers/LodDataBuilder.java

@@ -44,6 +44,7 @@ public class LodDataBuilder
 		
 		
 		ChunkSizedFullDataAccessor chunkData = new ChunkSizedFullDataAccessor(chunkWrapper.getChunkPos());
+		int minBuildHeight = chunkWrapper.getMinFilledHeight();
 		
 		for (int x = 0; x < LodUtil.CHUNK_WIDTH; x++)
 		{
@@ -71,7 +72,7 @@ public class LodDataBuilder
 				}
 				
 				
-				for (; y >= chunkWrapper.getMinBuildHeight(); y--)
+				for (; y >= minBuildHeight; y--)
 				{
 					IBiomeWrapper newBiome = chunkWrapper.getBiome(x, y, z);
 					IBlockStateWrapper newBlockState = chunkWrapper.getBlockState(x, y, z);
@@ -94,7 +95,7 @@ public class LodDataBuilder
 				}
 				longs.add(FullDataPointUtil.encode(mappedId, lastY - y, y + 1 - chunkWrapper.getMinBuildHeight(), light));
 				
-				chunkData.setSingleColumn(longs.toArray(new long[0]), x, z);
+				chunkData.setSingleColumn(longs.toLongArray(), x, z);
 			}
 		}
 		if (!canGenerateLodFromChunk(chunkWrapper)) return null;

core/src/main/java/com/seibel/distanthorizons/core/generation/DhLightingEngine.java

@@ -244,7 +244,7 @@ public class DhLightingEngine
 					continue;
 				}
 				
-				if (relNeighbourBlockPos.y < neighbourChunk.getMinBuildHeight() || relNeighbourBlockPos.y > neighbourChunk.getMaxBuildHeight())
+				if (relNeighbourBlockPos.y < neighbourChunk.getMinFilledHeight() || relNeighbourBlockPos.y > neighbourChunk.getMaxBuildHeight())
 				{
 					// the light pos is outside the chunk's min/max height,
 					// this can happen if given a chunk that hasn't finished generating

core/src/main/java/com/seibel/distanthorizons/core/wrapperInterfaces/chunk/IChunkWrapper.java

@@ -39,6 +39,12 @@ public interface IChunkWrapper extends IBindable
 	int getMinBuildHeight();
 	int getMaxBuildHeight();
 	
+	/**
+	 * returns the Y level for the first non-empty section in this chunk,
+	 * or {@link Integer#MAX_VALUE} if this chunk is completely empty.
+	 */
+	int getMinFilledHeight();
+	
 	/** @return The highest y position of a solid block at the given relative chunk position. */
 	int getSolidHeightMapValue(int xRel, int zRel);
 	/**