* CLI adhoc_task.php: new option --taskslimit
* CLI adhoc_task.php: --execute option is implied when other options are given
* core\task\manager::get_next_adhoc_task(): new param $number
for limiting number of tasks to run
* CLI adhoc_task.php: new option --id
* cron::run_adhoc_task($taskid) for running tasks by id
* core\task\manager::get_adhoc_task($taskid) for retreival/locking
Copy the CLI scripts from admin/tool/task/cli to admin/cli (schedule_task.php and adhoc_task.php)
and rename to scheduled_task.php and to improve in order to use cron_run_inner_scheduled_task.