Summary:
I was assuming the delegate would always be an IGListAdapterProxy, but this only happens if the client sets either the `collectionViewDelegate` or `scrollViewDelegate` properties on IGListAdapter. Otherwise the delegate will just be the IGListAdapter. Change the debug code to handle this case.

We were starting to see some debug logs roll in with the delegate class listed as IGListAdapter. Hopefully this will return the correct class now.

Differential Revision: D31690438

fbshipit-source-id: bf6dde57756fee4fe617944d45e152cae734b4f1

Summary:
As title, currently https://instagram.github.io/IGListKit/ is not working.

Let's try to rebuild the doc

Reviewed By: Ziewvater

Differential Revision: D31811862

fbshipit-source-id: 8a0b0ce6c73542da71dddd13c24b5eb9fe9b0506

…agram#1544)

Summary:
Pull Request resolved: Instagram#1544

Refactored and added functions to IGListAdapter for getting index path or scroll position of first visible item in list.

This makes it possible to see which item is the current first visible item scrolled to in the list, and determine how far it is scrolled into (analogous to additionalOffset in scrollToObject:).

Reviewed By: lorixx

Differential Revision: D32196398

fbshipit-source-id: d809d5f96bb4e1d95055dbebe4e55c1a428a40ed