Make cactus flowers harvestable (#1356)

Author: thorsten-fluegel

src/main/java/com/sk89q/craftbook/mechanics/ic/gates/world/blocks/CombineHarvester.java

@@ -86,6 +86,8 @@ public boolean harvestable(Block block) {
             case COCOA:
                 Ageable ageable = (Ageable) block.getBlockData();
                 return ageable.getAge() == ageable.getMaximumAge();
+            case CACTUS_FLOWER:
+                return below == Material.CACTUS;
             case CACTUS:
                 return below == Material.CACTUS && above != Material.CACTUS;
             case SUGAR_CANE: