QHeaderView - remove confusing bool

It is probably better not to have a default boolean in
QHeaderView::setResizeContentsPrecision

Task-number: QTBUG-34665

Change-Id: I0bb2c35abc1d5713bb3ee65df3af86c04f175a38
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>
Move QTreeView::accessibleTree2Index to the private class

It's not needed to expose that symbol.

Change-Id: I65b752a41d80eb0779969fa3887c081b4c2c88db
Reviewed-by: Jan Arve Sæther <jan-arve.saether@digia.com>