Make alternative falling block ground detection configurable

Workaround for GH-336

Spigot-Server-Patches/Make-entities-look-for-hoppers.patch

@@ -82,8 +82,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 --- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
 +++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
 @@ -0,0 +0,0 @@ public class PaperWorldConfig {
-             log("Old Cannon Behaviors: This feature may not be working entirely properly at the moment");
-         }
+     private void altFallingBlockOnGround() {
+         altFallingBlockOnGround = getBoolean("use-alternate-fallingblock-onGround-detection", false);
      }
 +
 +    public boolean isHopperPushBased;