Ensure that when setCollectionViewLayout is called, the new layout is used when computing attributes of the contained items.
Corrected/improved the hit detection of items within PSTCollectionViewFlowLayout.layoutAttributesArray.

The existing code would return all items in the row tapped rather than just the item.  The new code now correctly adjusts the rectangle used to detect an intersection and only includes those items that intersect.

This seems (to me) to be more consistent with the behaviour of the Apple classes.
Fixed the way the frame attribute value is maintained.  It was being set such that it's origin was the centre of the view which made it next to impossible to get a meaningful tap detection.
Merge pull request #394 from pkclsoft/master

Corrections/Improvements to selection of items in flow layout