Rename 'cleanup' to 'post'. We will have 'pre' and 'post' functions.
Implement cleanup functions, including 'mailto'.
Add Whentools library, test, documentation.
Refactor state into a separate [Whenstate] module. The new module contains all jobs and variables.
Split large 'Whenutils' module into two (creating new module 'Whenexpr').
Remove Whenutils.no_job_private and refactor prev-related code.
whenjobs initial version.