Fix highlighting behavior and reorganize how selection and highlighting iteract
fix incompatible pointer type warning for Deployment Targets >= iOS 6.0
Merge pull request #169 from mikevoyt/fixwarnings

fix incompatible pointer type warning for Deployment Targets >= iOS 6.0
Merge pull request #166 from taiyangc/highlight

Fix highlighting behavior and reorganize how selection and highlighting ...
Update header
- fix targetContentOffsetForProposedContentOffset:withScrollingVelocity: not called
- relay UIScrollViewDelegate methods to _collectionViewDelegate
Added invalidateLayout implementation for PSTCollectionViewLayout.m
Merge pull request #176 from r618/master

Added invalidateLayout implementation for PSTCollectionViewLayout
Fix to effectively ignoring contentInset with a small contentSize.
Removed the minimum contentSize setter in -[PSTCollectionViewFlowLayout updateItemsLayout].
PSTCVFlowLayout -updateItemsLayout takes into accout PSTGridLayoutSection.sectionMargins to set contentSize.
Merge pull request #177 from loganmoseley/master

-[PSTCollectionViewFlowLayout updateItemsLayout] changes to correct contentSize.
Merge pull request #170 from lono175/master

Fix "targetContentOffsetForProposedContentOffset:withScrollingVelocity:" not called
Preserve ivar layout.
Fixed createPreparedCellForItemAtIndexPath:layoutAttributes: not applying attributes
Fixed nil return from layoutAttributesForElementsInRect resulting in all cells being removed.
Merge pull request #179 from tyrone-sudeium/bugfix/nil-layout-attributes

Behaviour when layoutAttributesForElementsInRect is nil
Merge pull request #178 from tyrone-sudeium/bugfix/attributes-not-applied

CreatePreparedCellForItem... doesn't apply attributes.
Fixed cell highlighting inconsistences with iOS6, including the order and number of calls
Modified SelectionDelegateExample for better highlighting/selection debugging (in the future)