Terrain: Fix coordinate parsing (negative coords)

- Optimize readNextUShortsLittleEndian network reading method
- Various coordinate computation issues, negative chunk offsets
- Properly parse negative coordinates for block change events
- Properly reach ground if less than 1 block over the ground

MinecraftClient/Mapping/Chunk.cs

@@ -57,7 +57,7 @@ namespace MinecraftClient.Mapping
         /// <returns>The block</returns>
         public Block GetBlock(Location location)
         {
-            return this[((int)location.X) % Chunk.SizeX, ((int)location.Y) % Chunk.SizeY, ((int)location.Z) % Chunk.SizeZ];
+            return this[location.ChunkBlockX, location.ChunkBlockY, location.ChunkBlockZ];
         }
     }
 }