Remove TODO from region type definition

The spec and the example are out of sync, and this needs to be corrected. I took a crack at it, but it may need a bit of work to be completely correct.
Updated "direct" to be "direct_leading"

Similar to other commit. "direct" is not a valid part of the spec, and therefore should be made explicitly "direct_leading" or "direct_shared".
Merge pull request #14 from brentjanderson/patch-1

Remove TODO from region type definition