Recurring vacation responder

[msaladna]

Now that apnscp has an ability to perpetuate work, add the ability to users to set away/back in the panel by leveraging Horizon.

Beacon pseudo-code:

email_set_vacation_schedule [away: [f: 18], back: [m: 6]]
Set a schedule to be away from Friday after 6 PM locale-specific. Return by 6 AM Monday.

More advanced usage:
email_set_vacation_schedule '[away: [f: 18, 18], back: [m: 6, 6]]'
Set away 6 PM - 6 AM daily except for Friday, set away 6 PM, back 6 AM.

M/T/W/R/F/S/U to specify each day of the week.

email_set_vacation_schedule '[away: 2017-12-25 00:00:00, back: 2018-01-03 00:00:00]'

Accept unix timestamp or any parseable datetime

Back/away precedence: Date > Day of week > Time

[msaladna]

Moved to feedback.apiscp.com#31