Change Default Date for Tabular Reports with date parameter

[ODOT-RPTD-mb]

This is a functionality enhancement.
TNExT uses the current date as the default date in tabular reports
Change the default date to the middle of the 7+ contiguous day period where all feeds are active. This means that the default date will be tied to the selected GTFS database. It also implies that some work to identify the 7+ contiguous day period for each GTFS database, or failing that the "best" 7 contiguous days. I record of GTFS db without all feeds active for 7+ days would also be a useful outcome of this work.