[PATCH 0 of 5 filtering part 2] Filtering part 2: real usage

[Pierre-Yves David]

This series show the first implementation of filtering. Replacing custom revset
code by standard logic on filtered repo.

It also includes further fix that I made while playing with higher part of the
series.

After this series expect:

Part 3: Apply filtering on all usage of the repo as a server (peer, hg serve, hgweb)

    This will requires some optimisation and bugfix in hgweb.

Part 4: Apply `hidden` filtering on repo all the times

    Seems to mostly work as expected.