checkheads: pass "ispushed" function to the obsmarkers logic We are about to make "allfuturecommon" a set of revs instead of a set of nodes. The function updated in this patch do not needs to know about these details so we just pass it a 'ispushed(node)' function. This will simplify the next changeset.

profile: drop maybeprofile It seems sufficiently simple to use "profile(enabled=X)" to not justify having a dedicated context manager just to read the config. (I do not have a too strong opinion about this).

profile: support --profile in alias and abbreviated version (--prof) We now process the "--profile" a second time after alias has been processed and the command argument fully parsed. If appropriate we enable profiling at that time. In these situation, the --profile will cover less than if the full --profile flag was passed on the command line. This is better than the previous behavior (flag ignored) and still fullfil multiple valid usecases.

profile: make the contextmanager object available to the callers This will allow calling methods on the object in the code using the context manager.

profile: introduce a knob to control if the context is actually profiling This is a step toward allowing context where the profiling in enabled withing the context range. This also open the way to kill the dedicated "maybeprofile" context manager and keep only one of 'profile' and 'maybeprofile'.

profile: introduce a "start" method to the profile context The start method is doing all profiler setup and activation. It is currently unconditionally called by '__init__' but this will be made more flexible in later changesets.