Task-number: QTCREATORBUG-2976

Requested by con.

Utils::NavigationTreeView is created - as a base class for any Navigation Widget (Side Bar) tree view

Merge-request: 2167
Reviewed-by: Kai Koehne <kai.koehne@nokia.com>

Use symbol->line() && symbol->column() instead going through the
translation unit. That's also what CppEditor does in
jumpToOutlineElement().

Rename method[Overview] to outline

Don't show e.g. all the methods that are defined by the Q_OBJECT
macro in the outline. We skip these by checking for Symbol->isGenerated
in the two proxy models used.

Don't calculate the right QModelIndex twice.

There's no use synchronizing the same model twice.