Clean up hierarchy of rails

detector rail has fundamentally different functionality than activator and powered rails, so it's misleading to present the same APIs for both.
detector rail's 'powered' state is better referred to as 'activated', since it means the detector rail is actually _producing_ power, and not _receiving_ power.

src/block/utils/PoweredByRedstoneTrait.php

@@ -0,0 +1,36 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\block\utils;
+
+trait PoweredByRedstoneTrait{
+	protected bool $powered = false;
+
+	public function isPowered() : bool{ return $this->powered; }
+
+	/** @return $this */
+	public function setPowered(bool $powered) : self{
+		$this->powered = $powered;
+		return $this;
+	}
+}

src/block/utils/RailPoweredByRedstoneTrait.php

@@ -0,0 +1,43 @@
+<?php
+
+/*
+ *
+ *  ____            _        _   __  __ _                  __  __ ____
+ * |  _ \ ___   ___| | _____| |_|  \/  (_)_ __   ___      |  \/  |  _ \
+ * | |_) / _ \ / __| |/ / _ \ __| |\/| | | '_ \ / _ \_____| |\/| | |_) |
+ * |  __/ (_) | (__|   <  __/ |_| |  | | | | | |  __/_____| |  | |  __/
+ * |_|   \___/ \___|_|\_\___|\__|_|  |_|_|_| |_|\___|     |_|  |_|_|
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * @author PocketMine Team
+ * @link http://www.pocketmine.net/
+ *
+ *
+*/
+
+declare(strict_types=1);
+
+namespace pocketmine\block\utils;
+
+use pocketmine\block\BlockLegacyMetadata;
+
+trait RailPoweredByRedstoneTrait{
+	use PoweredByRedstoneTrait;
+
+	protected function writeStateToMeta() : int{
+		return parent::writeStateToMeta() | ($this->powered ? BlockLegacyMetadata::REDSTONE_RAIL_FLAG_POWERED : 0);
+	}
+
+	public function readStateFromData(int $id, int $stateMeta) : void{
+		parent::readStateFromData($id, $stateMeta);
+		$this->powered = ($stateMeta & BlockLegacyMetadata::REDSTONE_RAIL_FLAG_POWERED) !== 0;
+	}
+
+	protected function getConnectionsFromMeta(int $meta) : ?array{
+		return self::CONNECTIONS[$meta & ~BlockLegacyMetadata::REDSTONE_RAIL_FLAG_POWERED] ?? null;
+	}
+}