Fluid cleanup and performance improvements (#3581)

Use custom gui widget with custom synchronization for rendering fake fluid slots.

src/main/java/appeng/fluids/util/IAEFluidTank.java

@@ -0,0 +1,18 @@
+
+package appeng.fluids.util;
+
+
+import net.minecraftforge.fluids.capability.IFluidHandler;
+
+import appeng.api.storage.data.IAEFluidStack;
+
+
+public interface IAEFluidTank extends IFluidHandler
+{
+	void setFluidInSlot( final int slot, final IAEFluidStack fluid );
+
+	IAEFluidStack getFluidInSlot( final int slot );
+
+	int getSlots();
+
+}