Fix various bugs in calqlatr

It's still not a great example but at least it's somewhat usable now.
- added files to .pro so you see them all in Creator
- keypad is fixed size and the "tape" takes up the rest, so you can
  resize the window to be able to see long numbers
- you can flick the ListView (MouseArea not on top of the whole thing!)
- ListView scrolls to the bottom when you add numbers past the point
  that scrolling is necessary to see them
- Clear, sqrt and +/- keys are functional

Task-number: QTBUG-26556
Change-Id: I485e4123ad6c24ca64bad3efc3acfc14587268d8
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Alan Alpert <aalpert@blackberry.com>