Add shouldRender() to Potions that allows to hide them completely in the inventory

src/test/java/net/minecraftforge/debug/NoPotionEffectRenderTest.java

@@ -0,0 +1,29 @@
+package net.minecraftforge.debug;
+
+import net.minecraft.potion.Potion;
+import net.minecraft.potion.PotionEffect;
+import net.minecraft.util.ResourceLocation;
+import net.minecraftforge.fml.common.Mod;
+import net.minecraftforge.fml.common.event.FMLPreInitializationEvent;
+
+@Mod( modid = NoPotionEffectRenderTest.modID, name = "No Potion Effect Render Test", version = "0.0.0" )
+public class NoPotionEffectRenderTest {
+  public static final String modID = "nopotioneffect";
+
+  @Mod.EventHandler
+  public void preInit(FMLPreInitializationEvent event) {
+    TestPotion INSTANCE = new TestPotion(30, new ResourceLocation(modID, "test_potion"), false, 0xff00ff);
+  }
+
+  public static class TestPotion extends Potion {
+
+    public TestPotion(int potionID, ResourceLocation location, boolean badEffect, int potionColor) {
+      super(potionID, location, badEffect, potionColor);
+    }
+
+    @Override
+    public boolean shouldRender(PotionEffect effect) {
+      return false;
+    }
+  }
+}