iOS: don't scroll after inputItem has moved

If the inputItem moves, it typically means that the user
scrolls or flicks the focus item around. In that case
we should avoid scrolling the screen, otherwise they
will "cancel out" each other. Besides, when the user
flicks, he takes control over the whereabouts
on the screen anyway.

Change-Id: Iad0762965f9dcdbcca934ce6d90a8c1413ce3ca2
iOS: update keyboard layout upon focus transfer

When iOS transfers focus from one view to another, it
asks the new view for its UIKeyInput properties before
deciding how the keyboard should be configured.

For Qt, the same QUIView is used for the whole QWindow
which means that UIKit will not change the keyboard
configuration just because we change the focus object
in Qt, since the UIView does not change.

There seems to be no way to tell UIKit that the
keyboard needs to change becuse the UIKeyInput
properties has changed. To work around this, we
briefly resign first responder status, and grabs it
again, for the same QUIView.

Change-Id: I2d15cc0c928deb023e7da58ad4669b7099dce2cf