email reminder of event to participants

[hrj]

Not sure if this is a good idea, as it can be considered spamming.

There are two options to reduce the "spamming" accusation:

• Send reminder only to registered users.
• Have an option for notifications (for registered users).

[hiteshd]

From the beginning, it was thought that only 2 emails are sent per event. Once during RSVP, and once before the event as a reminder. To make it better, We can have a checkbox that says "Do you want to receive a reminder?"

[hiteshd]

ada5250 fixes this