lib/event: event_list_range now ignores the end time

When deciding which events to list, the only criteria is now that the start
time falls within the given range
add email to be sent some period of time before projects

I added a cron page which is meant to be called by cron every so often.
Right now, the only task accomplished by the page is to send a reminder
email for project some amount of time (2 days by default) before a
project.  Other tasks can be added to the page later.