Make Clear button in search field accessible

This requires the TextField to have children, so it relies on
a patch to QAccessibleQuickItem::childItems() to remove the condition
that returns an empty list if is has role EditableText (and friends)

Only tested with accerciser

Change-Id: I8f02837d440a19c109271fcac89989dfa0fd83ea
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@theqtcompany.com>
Un-abbreviate m/s, mph, mm and in for accessibility

There is currently only one translation (german)

Change-Id: I76abb04d842b91726d3052a94d8b81dbac1b10e8
Reviewed-by: Caroline Chao <caroline.chao@digia.com>
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@theqtcompany.com>