Minor bugfix to check for existence of user before accessing user methods.
Added event handling, message creation.
Built out message generation and dispatch.
Add/manage link text in subscription type config.
Add/manage link generation utility service.
Cache handling for entity subscription links.
Adds creation access check and cache tag handling for plugins.
Fix for access handler.
Access to view subscription types.
Alpha 1 release.
Basic subscription entity type, with bundles and fieldable.
Misc UI and access functionality.
Dev branch.
