[SB2] Removed unused include.
[SB2] More unused includes removed.
[Interfaces] Support Qt5 in IQuarkComponentProvider.
[SB2] Includes fixups.
[Util] Derive UnhideListViewBase from QQuickWidget in Qt5.
[SB2] More uses for auto type deduction.
[SB2] Qt5 compatibility (at least it builds).
[SB2] Use native Qt5 json parser on Qt5.
[Util] Removed HandleError() dumb stub.
[Util] Handle auth errors in VkAuthManager.

Happens if the saved data becomes corrupt for some reason, for example.