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

---
Want to back this issue? **[Post a bounty on it!](https://www.bountysource.com/issues/62656956-outline-plugin-should-differentiate-by-visibility-and-member-type?utm_campaign=plugin&utm_content=tracker%2F61917289&utm_medium=issues&utm_source=github)** We accept bounties via [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F61917289&utm_medium=issues&utm_source=github).