New trip creation: limit the calendar services available to present and future

[answerquest]

Trips listing : When creating a new trip, there is a dropdown picker for calendar service (keyed by service_id).

These services have an end date. Some gtfs feeds may contain some or many expired services whose end date is gone.

To de-clutter the options, remove such entries, whose end date is before current date, from the dropdown list.

[answerquest]

Done. What this entailed:

• introduced a GET URL parameter current=y in calendar API call. This parameter is passed in Trips page, but not at the actual Calendar table page.
• if the current parameter is received at backend, then a separate calendarCurrent() function is called instead of the regular readTableDB().
• calendarCurrent() function reads the calendar table from db, then filters it to only those rows that have end_date greater than or equal to the current system date.

Changed code will be pushed with release v2.1.0