[Qt-creator] Tab UI in Projects mode to TreeView

[Tasuku Suzuki]

Thanks all for positive feedback.

Let me summarize to move on.

* the change two level project tabs to a side tree
I see many people like the idea.

* look & feel
A simple tree view would be better to be consistent. I see applying a
hummer icon for each project works fine so far.

So, I want to finish the patch https://codereview.qt-project.org/121843


* moving Kits, Build and Run into the tree (or not)
We can continue the discussion.

* more exciting graphical design
This was not directly related to my proposal.
Jochen, could you start a new discussion if you love to change that?


Btw, someone can help updating the Qt Creator Manual later?
e.g. http://doc.qt.io/qtcreator/creator-configuring-projects.html

Best Regards,
--
Tasuku Suzuki