Permission: added removeChild()

this probably isn't useful at all, but it's best to provide alternatives for all the stuff that getChildren() could have been used for ...

src/permission/Permission.php

@@ -121,4 +121,10 @@ class Permission{
 		$this->children[$name] = $value;
 		$this->recalculatePermissibles();
 	}
+
+	public function removeChild(string $name) : void{
+		unset($this->children[$name]);
+		$this->recalculatePermissibles();
+
+	}
 }