contrib/revsetbenchmarks.txt

obsmarker: add a `flags` method

We introduce a proper method to access the flag information.

all()
draft()
::tip
draft() and ::tip
::tip and draft()
0::tip
roots(0::tip)
author(lmoscovicz)
author(mpm)
author(lmoscovicz) or author(mpm)
author(mpm) or author(lmoscovicz)
tip:0
max(tip:0)
min(0:tip)
0::
min(0::)
roots((tip~100::) - (tip~100::tip))
::p1(p1(tip))::
public()
:10000 and public()
draft()
:10000 and draft()
max(::(tip~20) - obsolete())
roots((0:tip)::)