Add comment to tracees_consistent.
Move scheduling-related Session code to RecordSession.
Rename Session::track to Session::on_create to match on_destroy.
Move on_create/on_destroy scheduling logic from Session to RecordSession.
Move scheduling data from Session to RecordSession.
Specialize EmuFs to ReplaySession.
Remove unused Session::dump_all_tasks.
Move scheduler typedefs from Session to RecordSession.
Move Session::create_tg to a static function in Task.cc.