SDS:Edit resources.php

The resources dropdown now shows resources with is_current = 'Y', which will allow us to retire resources.

The weekly resource booking will now default show the booking times from start_time (rounded down to the start of the hour) up to end_time (or the start of the next hour). A quirk of Alex's code is that it is not possible to start the day at midnight, but only at $start_time > midnight + $display_increment. Days may end at midnight.

Alex had hard-coded the page to show half-hour increments: it is now possible to use $display_increment to show 1 hour, 30 minute, 20 minute, 12 minute and 10 minute increments (just as long as $display_increment divides evenly into 60).