Merge pull request #1 from duncandee/master

Section click listeners & Section item listeners
Allow section header view type ids and item view type ids to clash. Remove getSectionItem method
Build again android-17
Cache internal calculated values. Fix bug with view type ids
Reset the caches before we call the super methods of notifyDataSet*
More caching of internal values.
Update the README to be more detailed
Fix a typo, bad variable names
Fix setOnScrollListener.
Fix header view added through addHeaderView. fixes #2
Reformat code
Merge branch 'master' of github.com:JimiSmith/PinnedHeaderListView

Conflicts:
	library/src/za/co/immedia/pinnedheaderlistview/PinnedHeaderListView.java