Enhancement for incomplete temporal data

[MSherif]

I propose to have a pre-processing function to complete the date given a partial date in form of

• year or
• year/month. For completion of date is done either by
• toBeginDate converts 2017 to 2017-01-01T09:00:00+00:00, and 2017-05 to 2015-05-00T00:00:00+00:00
• toEndDate converts 2017 to 2017-12-31T23:59:59+00:00, and 2017-05 to 2017-05-31T23:59:59+00:00

[kvndrsslr]

This will be considered in the upcoming rewrite