Typehinted up entity API

Did you guys think ALPHA7 changes were done?!
Sone stuff still needs some work, most notably data-properties can't be typed yet because they are just mushed into a couple of methods.

src/pocketmine/command/CommandSender.php

@@ -42,7 +42,7 @@ interface CommandSender extends Permissible{
 	/**
 	 * @return string
 	 */
-	public function getName();
+	public function getName() : string;
 
 	/**
 	 * Returns the line height of the command-sender's screen. Used for determining sizes for command output pagination