Allow a nil data source.
Merge pull request #55 from github/nil-datasource

Allow a nil data source.
Don't implement -keyDown:.
Merge pull request #60 from github/keydown

Don't implement -keyDown:
Merge branch 'master' into fix-headers
make JNWCollectionView.h the umbrella header, rename class header

This is done since JNWCollectionView.h should technically be an
umbrella header, and there's no way for that to happen unless I rename
the current JNWCollectionView.h to something else, since I'd cyclic
imports if I tried to import everything into the current header.
rename all of the internal imports to use the new header name
add the umbrella header
update the imports in the demo to use the umbrella header
Merge pull request #62 from jwilling/fix-headers

Add an umbrella header, rename current header.
turn the collection view flags into proper bitfields
Merge pull request #63 from jwilling/bitfields

Make flags proper bitfields
just get the index path from the cell itself

Fairly certain this was originally written because I didn't have a
property to access the index path on the cell. Now it's unneeded.
update the xccheckout file for JNWScrollView
Merge pull request #64 from jwilling/simplify-indexPathForCell

Simplify -indexPathForCell:
Use autoresizingMask instead of overriding -layout
Merge pull request #65 from mdiep/work-with-autolayout

Work with Auto-Layout
Fix crash when using list layout (#68).

- Cause and fix found by @mrjjwright.
Make it possible to clear a cell’s background.

- Before this change it was not possible to clear a cell’s background
after having set either the background image or color.
Merge pull request #71 from rastersize/fix-list-layout-calloc

Fix crash when using list layout (#68).