Birthday calendar

[myrkvi]

Add a feature in which users on a server can register their birthday, and the bot will congratulate the user on the birthday.

• User should be able to
  • register birthday. The year should be optional.
  • remove their birthday from the list.
  • request upcoming birthdays.
• Admins should be able to
  • configure when the announcement is made
  • configure which channel the announcement should be made in
  • enable and disable the feature

[adalinesimonian]

Anyone with a registered birthday should have it deleted upon leaving the server, on privacy grounds.