select Date/ Daterange pro programmatically 

Hey,

in addition to my previous feature request, the next step for non-static use-cases would be to have an option to select a date/ date range programmatically.

It could be a simple method that takes a date or a daterange and returns all classes for that are set on the date/ date range.

If you have some time, could you probably implement that too? Would be awesome.

Thanks 
