Mark old liquid system as deperated to be removed next Minecraft release.

common/net/minecraftforge/liquids/IBlockLiquid.java

@@ -8,6 +8,7 @@ import net.minecraft.nbt.NBTTagCompound;
  * @author cpw
  *
  */
+@Deprecated //See new net.minecraftforge.fluids
 public interface IBlockLiquid extends ILiquid {
     /**
      * Controls the type of block that is generated by this IBlockLiquid

common/net/minecraftforge/liquids/ILiquid.java

@@ -13,6 +13,7 @@ package net.minecraftforge.liquids;
  * Liquids implement this interface
  *
  */
+@Deprecated //See new net.minecraftforge.fluids
 public interface ILiquid {
 
     /**

common/net/minecraftforge/liquids/ILiquidTank.java

@@ -5,6 +5,7 @@ package net.minecraftforge.liquids;
  *
  * @author cpw
  */
+@Deprecated //See new net.minecraftforge.fluids
 public interface ILiquidTank {
 
     /**

common/net/minecraftforge/liquids/ITankContainer.java

@@ -1,7 +1,7 @@
 package net.minecraftforge.liquids;
 
 import net.minecraftforge.common.ForgeDirection;
-
+@Deprecated //See new net.minecraftforge.fluids
 public interface ITankContainer {
 
     /**

common/net/minecraftforge/liquids/LiquidContainerData.java

@@ -11,7 +11,7 @@ package net.minecraftforge.liquids;
 
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
-
+@Deprecated //See new net.minecraftforge.fluids
 public class LiquidContainerData {
 
     public final LiquidStack stillLiquid;

common/net/minecraftforge/liquids/LiquidContainerRegistry.java

@@ -12,7 +12,7 @@ import java.util.Set;
 import net.minecraft.block.Block;
 import net.minecraft.item.Item;
 import net.minecraft.item.ItemStack;
-
+@Deprecated //See new net.minecraftforge.fluids
 public class LiquidContainerRegistry
 {
     public static final int BUCKET_VOLUME = 1000;

common/net/minecraftforge/liquids/LiquidDictionary.java

@@ -16,6 +16,7 @@ import com.google.common.collect.ImmutableMap;
  *
  * @author CovertJaguar <railcraft.wikispaces.com>
  */
+@Deprecated //See new net.minecraftforge.fluids
 public abstract class LiquidDictionary
 {
 

common/net/minecraftforge/liquids/LiquidEvent.java

@@ -4,7 +4,7 @@ import net.minecraft.tileentity.TileEntity;
 import net.minecraft.world.World;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.event.Event;
-
+@Deprecated //See new net.minecraftforge.fluids
 public class LiquidEvent extends Event {
     public final LiquidStack liquid;
     public final int x;

common/net/minecraftforge/liquids/LiquidStack.java

@@ -22,6 +22,7 @@ import net.minecraft.util.Icon;
  *
  * @author SirSengir
  */
+@Deprecated //See new net.minecraftforge.fluids
 public class LiquidStack
 {
     public final int itemID;

common/net/minecraftforge/liquids/LiquidTank.java

@@ -6,6 +6,7 @@ import net.minecraft.tileentity.TileEntity;
 /**
  * Reference implementation of ILiquidTank. Use this or implement your own.
  */
+@Deprecated //See new net.minecraftforge.fluids
 public class LiquidTank implements ILiquidTank {
     private LiquidStack liquid;
     private int capacity;