log cases where node plugin defines an invalid nodeEditorClassName
test if CG context is nil (Apple recommendation)
assert when plugin node property name does not exist
improved CCNode description
Merge pull request #203 from jtwigg/develop

Develop
Merge pull request #202 from KoboldKit/develop

Additional checks for errors (incorrect node property name, CG context being nil), improved CCNode description
Merge pull request #208 from jtwigg/develop

Develop
Merge branch 'develop' of https://github.com/apportable/SpriteBuilder into develop