Fluid cleanup and performance improvements (#3581)

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

src/main/java/appeng/client/gui/widgets/GuiCustomSlot.java

@@ -0,0 +1,85 @@
+
+package appeng.client.gui.widgets;
+
+
+import net.minecraft.client.Minecraft;
+import net.minecraft.client.gui.Gui;
+import net.minecraft.entity.player.EntityPlayer;
+import net.minecraft.item.ItemStack;
+
+
+public abstract class GuiCustomSlot extends Gui implements ITooltip
+{
+	private final int x;
+	private final int y;
+	private final int id;
+
+	public GuiCustomSlot( final int id, final int x, final int y )
+	{
+		this.x = x;
+		this.y = y;
+		this.id = id;
+	}
+
+	public int getId()
+	{
+		return id;
+	}
+
+	public boolean canClick( final EntityPlayer player )
+	{
+		return true;
+	}
+
+	public void slotClicked( final ItemStack clickStack, final int mouseButton )
+	{
+	}
+
+	public abstract void drawContent( final Minecraft mc, final int mouseX, final int mouseY, final float partialTicks );
+
+	public void drawBackground( int guileft, int guitop )
+	{
+	}
+
+	@Override
+	public String getMessage()
+	{
+		return null;
+	}
+
+	@Override
+	public int xPos()
+	{
+		return this.x;
+	}
+
+	@Override
+	public int yPos()
+	{
+		return this.y;
+	}
+
+	@Override
+	public int getWidth()
+	{
+		return 16;
+	}
+
+	@Override
+	public int getHeight()
+	{
+		return 16;
+	}
+
+	@Override
+	public boolean isVisible()
+	{
+		return false;
+	}
+
+	public boolean isSlotEnabled()
+	{
+		return true;
+	}
+
+}