Feature Request: Anacron support to allow for the device to be powered off without missing scans.

[Lazerbeak12345]

Is your feature request related to a problem? Please describe.
If the time window indicated by the crontab entry generated by clamtk is missed, it won't get hit until next time.

This can be a problem when the frequency is set really low.

User story:

• Install and configure clamTK on something like a laptop, configured to run weekly, on saturday at lunchtime.
• Ensure computer is off during that time
• Clamtk won't run till next week at that time (idealy)

Describe the solution you'd like
Anacron Is an alternative to cron that "[u]nlike cron(8), it does not assume that the machine is running continuously. Hence, it can be used on machines that aren't running 24 hours a day, to control regular jobs as daily, weekly, and monthly jobs.

Here's why I think this would fix the problem:

For each job, Anacron checks whether this job has been executed in the last n days, where n is the period specified for that job. If not, Anacron runs the job's shell command, after waiting for the number of minutes specified as the delay parameter.

Describe alternatives you've considered
A startup script for each init system (systemd, runit, s6, OpenRC and SysV). Could be a heavy lift.

Additional context
I am aware that camtk currently isn't maintained. I'm requesting this feature in hopes that the next steward of the codebase would be available to consider this feature request.

I think that whether cron or anacron is used should be a choice presented to the user.

A downside to this is that the anacron script will increase the number of scripts running while the system starts.