Block light bug fixes (#454)

* Fixed an age-old light calculation bug causing solid blocks to filter their own light, fixed #375, probably fixed #288
Light spread reduction should be done based on the _target's_ light filter level, not the source.

* Revert "Fix Glowing Obsidian lighting"
This hack is no longer necessary.
This reverts commit 35c33ba980.

* Fixed wrong light levels for torch and redstone torch

* Take adjacent light levels and opacity changes into account, block light will now spread when an obstruction is removed, close #455

* Added timings for Level->setBlock() and lighting updates

src/pocketmine/block/GlowingObsidian.php

@@ -22,7 +22,7 @@
 namespace pocketmine\block;
 
 
-class GlowingObsidian extends Transparent{
+class GlowingObsidian extends Solid{
 
 	protected $id = self::GLOWING_OBSIDIAN;
 

src/pocketmine/block/RedstoneTorch.php

@@ -32,4 +32,8 @@ class RedstoneTorch extends Torch{
 	public function getName(){
 		return "Redstone Torch";
 	}
+
+	public function getLightLevel(){
+		return 7;
+	}
 }

src/pocketmine/block/Torch.php

@@ -34,7 +34,7 @@ class Torch extends Flowable{
 	}
 
 	public function getLightLevel(){
-		return 15;
+		return 14;
 	}
 
 	public function getName(){