added the CfgPackage class
added Scheduler.schedule_command()
added the Command and CmdInstall classes
added the scheduler main loop
scheduler: started the next pool when needed
scheduler: start next task when needed
scheduler: processed pending tasks
scheduler: terminated finished pools
added some repr()
added task dependencies
added Task.state
fixed TaskPool.get_next_task()
added the CfgTarget class
added the CfgBuild class
added the CfgSource class
added the Behaviour classes
implemented BhvBootstrapGNU.run()
added Behaviour.check_run()
added the CfgItem class and the get/set_state() methods
added the DBFile class