New Categories & Tests

- Tests show that arrays support IReadOnlyList<T> in .Net 4.5 (not in .Net 4.0).
The extension AsReadOlyList is definitely a Must :-).
Edited Readme.md.
Fix comments (100% done).

- New TypeForwarding for IReadOnlyCollection/IReadOnlyList.
- 2.8.7-develop version.