Fix delayed animation with zero duration

If you specify zero duration and zero delay, the animations will be
instant and will not be scheduled for next runloop cycle. This was
causing view to jump to their position when not animated.

You can now use `animated? 0.25 : 0` safely for animation duration.
Merge branch 'master' of https://github.com/iMartinKiss/KeepLayout

* 'master' of https://github.com/iMartinKiss/KeepLayout:
  Fix warnings after last merge