World: fixed block placement when clicking on replaceable blocks

in vanilla, it appears to behave as if the player always clicked on the up face if a block was replaced.

In PM, we were still using the original face, which caused bugs when, for example, placing a button next to a wall by clicking on the side of tallgrass. The button would replace the tallgrass, but stick to the wall, instead of placing itself on the ground like vanilla expects.

This may appear unusual to anyone who also happens to implement canBePlacedAt(), since the facing behaviour will be different. However, this behaviour appears to match vanilla, and even slabs (which I feared might break because of this change) work perfectly.

In the future, it may be desirable to pass some other value here, such as null, to indicate that the clicked block is being replaced. However, that's a BC break and therefore outside of the scope of a stable bug fix.

src/block/Torch.php

@@ -74,10 +74,7 @@ public function onNearbyBlockChange() : void{
 	}
 
 	public function place(BlockTransaction $tx, Item $item, Block $blockReplace, Block $blockClicked, int $face, Vector3 $clickVector, ?Player $player = null) : bool{
-		if($blockClicked->canBeReplaced() && $this->canBeSupportedBy($blockClicked->getSide(Facing::DOWN), Facing::UP)){
-			$this->facing = Facing::UP;
-			return parent::place($tx, $item, $blockReplace, $blockClicked, $face, $clickVector, $player);
-		}elseif($face !== Facing::DOWN && $this->canBeSupportedBy($blockReplace->getSide(Facing::opposite($face)), $face)){
+		if($face !== Facing::DOWN && $this->canBeSupportedBy($blockReplace->getSide(Facing::opposite($face)), $face)){
 			$this->facing = $face;
 			return parent::place($tx, $item, $blockReplace, $blockClicked, $face, $clickVector, $player);
 		}else{

src/world/World.php

@@ -58,6 +58,7 @@
 use pocketmine\item\VanillaItems;
 use pocketmine\lang\KnownTranslationFactory;
 use pocketmine\math\AxisAlignedBB;
+use pocketmine\math\Facing;
 use pocketmine\math\Vector3;
 use pocketmine\nbt\tag\IntTag;
 use pocketmine\nbt\tag\StringTag;
@@ -1955,6 +1956,10 @@ public function useItemOn(Vector3 $vector, Item &$item, int $face, ?Vector3 $cli
 
 		if($hand->canBePlacedAt($blockClicked, $clickVector, $face, true)){
 			$blockReplace = $blockClicked;
+			//TODO: while this mimics the vanilla behaviour with replaceable blocks, we should really pass some other
+			//value like NULL and let place() deal with it. This will look like a bug to anyone who doesn't know about
+			//the vanilla behaviour.
+			$face = Facing::UP;
 			$hand->position($this, $blockReplace->getPosition()->x, $blockReplace->getPosition()->y, $blockReplace->getPosition()->z);
 		}elseif(!$hand->canBePlacedAt($blockReplace, $clickVector, $face, false)){
 			return false;