clfilter: remove use of xrange in revset For changelog level filtering to take effect it need to be used for any iteration. Some remaining use of `xrange` in revset code is replace by proper use of `changelog.revs` or direct iteration over changelog.

largefile: use `self` in repo method instead of `repo` Most method added (or overwritten) to repo by largefile works on `repo` instead of `self`. This currently works without trouble because `self` and `repo` are likely the same. However this is semantically dubious and this may cause issue for filtering. `self` may be proxy object different from the `repo` one. This changeset fix that and use `self` when applicable.

test: use proper subclassing in `test-issue2137.t`. To use changelog filtering on the repository, we plan to use "proxy" object that perfectly mock a repository but with a filtered changelog. Altering the `repo.commit` function using `extensions.wrapfunction` will prevent the logic to propagate to the proxy class by the mean of inheritance. We changes the extension to use subclassing as expectable.