トリプルポインタ化
Merge branch 'master' of https://github.com/ashidome/Paint-BuiLder---.git
デストラクタ仮

Signed-off-by: Naoya Kikuchi <ashidome@gmail.com>
Merge branch 'master' of https://github.com/ashidome/Paint-BuiLder---.git
レイヤー

Signed-off-by: Naoya Kikuchi <ashidome@gmail.com>
Merge branch 'master' of https://github.com/ashidome/Paint-BuiLder---.git