Add support for L and W as specified in Quartz

[niondir]

Like specified here: http://www.quartz-scheduler.org/documentation/quartz-2.3.0/tutorials/crontrigger.html

We will need an implementation that supports "L" and "W" characters.

We might schedule it for internal development and provide a pull request. If anyone has started on this topic, feedback is welcome.

[exander77]

I have made my own fork (to build super tiny cron daemon) that covers these features. Feedback appreciated: https://github.com/exander77/supertinycron

[staticlibs]

This project is no longer maintained, see its updated and extended fork in exander77/supertinycron repo, closing the issue to archive the repo.