Change git clone url to facebook/regenerator
Merge pull request #115 from chenglou/patch-1

Change git clone url to facebook/regenerator in README.md.
Add an assertion that fails because wrapGenerator.mark not called.
Make the lib/visit traversal a post-order traversal.

This ensures we have fully dealt with all nested generators before
transforming outer generators.
Pass the outer function to wrapGenerator along with the innerFn.

Note to self: this argument will probably need to be null in the async
function case, since the outer function is not actually a generator
function there.
Turn generator function declarations into named, hoisted function expressions.
Borrow a failing test from Traceur that manifests #113.
Fix generator function prototype object model.

Closes #113.