Prefix Essentials 2.4.1

Added the ability to create a custom, prefix-specific action button at the top of all threads with that prefix to expire the prefix. It's the same as editing the thread and changing the prefix, but easier for users. The permissions are based on thread edit permissions.

Using the new custom prefix action button is the same as editing the thread and changing the prefix, but easier for users. The permissions are based on thread edit permissions.