Migrate legacy Block references to MantleBlock

src/main/java/tconstruct/blocks/SlabBase.java

@@ -2,6 +2,7 @@ package tconstruct.blocks;
 
 import java.util.List;
 
+import mantle.blocks.MantleBlock;
 import net.minecraft.block.Block;
 import net.minecraft.block.material.Material;
 import net.minecraft.client.renderer.texture.IconRegister;
@@ -16,7 +17,7 @@ import tconstruct.library.TConstructRegistry;
 import cpw.mods.fml.relauncher.Side;
 import cpw.mods.fml.relauncher.SideOnly;
 
-public class SlabBase extends Block
+public class SlabBase extends MantleBlock
 {
     Block modelBlock;
     int startingMeta;