Major Refactoring of Bootstrap Code (#75)

- Refactored boostrap code:
  * Completely reworked item/block/tile registration.
  * Fixed server side startup.
  * Fixed server side startup.
  * More documentation.
  * More heavy cleanup
  * More cleanups.
  * Major refactoring of state mapping and fixes a lot of other issue related to item rendering.
  * Fixes sky chest item models (no item TESR).
  * Only use CachingRotatingBakedModel for tile entities automatically.
  Fix default rotation of quartz pillar for item model.
  * Used method reference instead of lambda for ItemMeshDefinition for multiparts.
  * Removed unnecessary IHasSpecialItemModel
  * Removed unused IconReg class.
  * Updated resource pack version.

src/main/java/appeng/block/networking/BlockEnergyCellRendering.java

@@ -0,0 +1,62 @@
+package appeng.block.networking;
+
+
+import net.minecraft.client.renderer.block.model.ModelResourceLocation;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.ResourceLocation;
+
+import appeng.api.implementations.items.IAEItemPowerStorage;
+import appeng.block.AEBaseItemBlockChargeable;
+import appeng.bootstrap.BlockRenderingCustomizer;
+import appeng.bootstrap.IBlockRendering;
+import appeng.bootstrap.IItemRendering;
+import appeng.tile.networking.TileEnergyCell;
+
+
+public class BlockEnergyCellRendering extends BlockRenderingCustomizer
+{
+
+	private final ResourceLocation baseModel;
+
+	public BlockEnergyCellRendering( ResourceLocation baseModel )
+	{
+		this.baseModel = baseModel;
+	}
+
+	@Override
+	public void customize( IBlockRendering rendering, IItemRendering itemRendering )
+	{
+		itemRendering.meshDefinition( this::getItemModel );
+		// Note: Since we use the block models, we dont need to register custom variants
+	}
+
+	/**
+	 * Determines which version of the energy cell model should be used depending on the fill factor
+	 * of the item stack.
+	 */
+	private ModelResourceLocation getItemModel( ItemStack is )
+	{
+		double fillFactor = getFillFactor( is );
+
+		int storageLevel = TileEnergyCell.getStorageLevelFromFillFactor( fillFactor );
+		return new ModelResourceLocation( baseModel, "fullness=" + storageLevel );
+	}
+
+	/**
+	 * Helper method that returns the energy fill factor (between 0 and 1) of a given item stack.
+	 * Returns 0 if the item stack has no fill factor.
+	 */
+	private static double getFillFactor( ItemStack is )
+	{
+		if( !( is.getItem() instanceof IAEItemPowerStorage ) )
+		{
+			return 0;
+		}
+
+		AEBaseItemBlockChargeable itemChargeable = (AEBaseItemBlockChargeable) is.getItem();
+		double curPower = itemChargeable.getAECurrentPower( is );
+		double maxPower = itemChargeable.getAEMaxPower( is );
+
+		return curPower / maxPower;
+	}
+}