Add option (defaulted to old behavior) to flip when needed:

* Flips the guider horizontally and/or vertically to avoid going off
the top, left, or right of screen.
* Move styleArrow call accordingly.
* Add public method guiders.getFlippedPosition which is used for this,
but can be reused for other purposes if needed.

Change-Id: I4a0e8df116bd2a278c9193eb43a9d13bd3957f66