only set listener if mOnHeaderClickListener != null
in case we need it
the case child.getTop() == stickyHeaderTop() is bad because it would

transform the sticky header to "hidden" (transform y = -100%) when it shouldn't
reset mHeader transform when swaping so that if it is reused

it has the right transform
Refactoring to allow better use with ListViewAnimations
abstract StickyListHeadersListViewAbstract to custom mList class
fix measure so that it animates correctly
Merge remote-tracking branch 'origin/master' into reuse_header

Conflicts:
	library/src/se/emilsjolander/stickylistheaders/StickyListHeadersListView.java