cron(8) related summer of code project

[Pavel Prokharau]

I was thinking about updating our cron(8) implementation. This project is
mentioned in ideas list
http://www.freebsd.org/projects/ideas/#p-cron-and-atrun.

For now my proposal is following:

* update the code base to ISC (OpenBSD already has it for a while)

* incorporate changes other BSDs has. First of all it's trivial security
fixes OpenBSD has (like strcpy -> strlcpy)

* atrun(8) improvements as mentioned on ideas page

* add privilege separation to cron(8). Its code base is really old and
likely to have security bugs.

I'd like this work to be done a summer of code project. But I'm not sure
if amount of work proposed sufficient for summer of code.

If you have some ideas about further improvements to cron(8) I'd be glad
hear them and work on it.

Pavel