Block: fixed use of full meta as variant in several cases

fixes #2940

now I need to go to the bathroom and wash this off my hands ... I'd forgotten how nasty this code is

src/pocketmine/block/StainedGlass.php

@@ -30,6 +30,6 @@ class StainedGlass extends Glass{
 	protected $id = self::STAINED_GLASS;
 
 	public function getName() : string{
-		return ColorBlockMetaHelper::getColorFromMeta($this->meta) . " Stained Glass";
+		return ColorBlockMetaHelper::getColorFromMeta($this->getVariant()) . " Stained Glass";
 	}
 }