Removes a whitespace and an unnecessary import
Removes OverdueScheduler companion object apply method
Adds Backlog Scheduler and changes command line to have 2 more schedulers.

My friend began using the program and desired not to over-contact people, thus
the Backlog scheduler will not yield any entries when you are "caught up" with
contacting people.

The Random Scheduler was already written, just lacking exposure through the
interface.
Adds unit test for Backlog Scheduler
Adds feature request for more flexible date parsing