[Feature Request] Ability to fetch a single page of items in a list

Would be nice to be able to fetch only a page of repositories, repo commits, and other lists instead of fetching the entire thing every time. Currently they call into _requestAllPages which automatically fetches everything from github, which can take awhile for long lists.

@mtscout6 suggested on gitter that a generator function would be a good way to accomplish this.

If there's a good direction to go in, I can probably work on this.

Start by tracing how repository, commit, and other list methods call _requestAllPages. Review the suggested generator-function direction and determine how callers can request a single page without changing existing full-fetch behavior. Done means list APIs support bounded pagination and the behavior is clear for long GitHub lists.

索引モデルが issue の本文から書いたものです。