fix a few spelling mistakes in docs and examples
Merge pull request #83 from sanga/fix_typos

fix a few spelling mistakes in docs and examples
handle if setUpClass is parent class under multiprocess
Merge pull request #85 from sanga/fix_multiprocess_class_fixutres

handle if setUpClass is parent class under multiprocess
Added missing documentation about the layer's description attribute

It might need rephrasing but I had to look through the code to find it.
Made the layer's description change more visible.
Merge pull request #86 from thedrow/patch-1

Added missing documentation about the layer's description attribute