.arcconfig

diff: pass a diff hunks filter function from changeset_printer to patch.diff()

We add a 'hunksfilterfn' keyword argument in all functions of the call
stack from changeset_printer.show() to patch.diff(). This is a callable
that will be used to filter out hunks by line range and will be used in
the "-L/--line-range" option of "hg log" command introduced in the
following changesets.

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}