Added upside-down stairs

src/API/BlockAPI.php

@@ -491,6 +491,10 @@ class BlockAPI{
 			case 53://Stairs
 			case 67:
 			case 108:
+			case 109:
+			case 114:
+			case 128:
+			case 156:
 				$faces = array(
 					0 => 0,
 					1 => 2,
@@ -498,6 +502,9 @@ class BlockAPI{
 					3 => 3,
 				);
 				$data["meta"] = $faces[$direction] & 0x03;
+				if(($data["y"] - 1) > $entity->y){
+					$data["meta"] |= 0x04; //Upside-down stairs
+				}
 				break;
 			case 96: //trapdoor
 				if(isset(Material::$transparent[$target[0]])){

src/classes/Data.php

@@ -129,6 +129,7 @@ class Material{
 		109 => true,
 		114 => true,
 		128 => true,
+		156 => true,
 	);
 	static $replaceable = array(
 		0 => true,
@@ -235,6 +236,8 @@ class Material{
 		108 => true,
 		112 => true,
 		114 => true,
+		128 => true,
+		156 => true,
 		246 => true,
 		247 => true,
 	);