Outline plugin should differentiate by visibility and member type

I'm documenting a vala project and I realised that the reason why outline has been so useless to me is that when I'm using outline to review the code of a class I've been trying to understand an instance of I just need the public members not the internal stuff but there's no clear way to understand what's public or private from the outline plugin. I had a few ideas about how to fix this but it's a design task, and I don't really do mockups.

- icons: most aesthetic, requires excessive design
- collapsible tree for public and private: gets stuff out of the way
- format the labels in UML: quick, easy, unambiguous, not beginner friendly

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まず outline プラグインと、issue で提案されている 3 つのアプローチ（アイコン、折りたたみ可能な public/private グループ、UML 形式のラベル）を確認します。最初にデザインの方向性を決定してください。完了とは、outline が可視性とメンバーの種類によってメンバーを明確に区別し、選択した表示方法についてプロジェクト内で合意されている状態です。

索引モデルが issue の本文から書いたものです。