Julia implementation of more advanced schedulers

[scls19fr]

This is out of the scope of this project (which is simply a port of Python sched), but Julia implementation of more advanced schedulers with support of periodic jobs or a number of times, support of cron syntax, support of several kind of executors, job stores... may be considered

Inspiration could be find with

• Python
  • APScheduler
  • schedule
  • python-crontab
  • croniter
• Ruby https://www.ruby-toolbox.com/categories/scheduling.html
  • rufus-scheduler
  • whenever
  • crono
  • resque-scheduler
  • clockwork
• PHP
  • crunz
  • php-cron-scheduler
    • cron-expression

See also https://discourse.julialang.org/t/julia-cron-like-event-scheduler/6899
https://stackoverflow.com/questions/46730044/what-is-the-julia-equivalent-to-pythons-schedule-package/46744455#46744455

[scls19fr]

See https://github.com/scls19fr/ExtensibleScheduler.jl (WIP)