signup 5.x-2.1

There are 2 major changes since 5.x-2.0: a long-awaited new feature, and a critical bug fix for anonymous users:

• #32482: Adding support for signup limits per node:
  • New field on site-wide signup defaults and per-node edit form to set or modify the signup limit.
  • Signups auto-close when the limit is reached.
  • Users can now cancel their own signup when signups are closed, and if it's not an event-enabled node, or the event hasn't started yet, signups automatically re-open.
  • Cleanup of the node/N/signups UI.
  • Even bigger cleanup of admin/content/signups UI.
  • Views support updated to view and filter by signup limit.
• #138401: Fixed a fatal PHP error on certain pages for anonymous users when caching is enabled.