Navigation side bar: It is "View", not "Pane"

Change-Id: Ic6a2f953089a58a8aaa432b9edeb7f6357d527f6
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Add index and filter combo box to external help window

Change-Id: Icc815379220c55d9d7dc5d154278ba21ce2e9984
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>
(Help)SideBar fixes

1. Get rid of the need to remember the side bar items, instead use the
IDs for activation.
2. Fix issue with empty side bar that cannot be shown, if settings exist
but contain invalid item IDs.
3. Use actual IDs instead of translated window titles for item IDs. This
requires using a different settings group to avoid issues with 2. when
going back to earlier versions of Qt Creator.

Change-Id: I1a760aa5a019db3231803af1bb72f83db49ba6b0
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>
Help Window: Add Bookmarks view

Change-Id: I8b4db5b3208c4133466fe4e61f1dd1f18b432fea
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>