[core] Perform haptic feedback on long press
[core] Play sound effect on item click
[layouts] Draw vertical dividers on top of the horizontal ones
[layouts] Fix DividerItemDecoration's constructor argument name
[layouts] Support different drawables for vertical and horizontal dividers

Fixes #86
[layouts] Correctly handle padding in SpannableGridLayoutManager

Fixes #87
[core] Implement pluggable support for item selection
[core] Update on-screen views on clearChoices() calls
[core] Change ItemSelectionSupport to always consume long clicks
[core] Move haptics/sound feedback to ItemClickSupport
[core] Use GestureDetectorCompat in ClickItemTouchListener