Prefix Essentials featuring auto expiring prefixes and prefix filtering 2.5.4

Fix "call to undefined method" error for New Posts page

When users ignore specific prefixes via their preferences, threads with those prefixes were still being shown in the Similar threads box and Search threads widget. That no longer happens.

Just a small change.
The default expiring value of new prefixes is set to never.

Added an admin option to

• force the prefix of question type threads to have a specified prefix and
• force the prefix of solved question type threads to have a specified prefix

/admin.php?options/groups/prefixess/

The idea is that it's easier then for people to find question and solved threads using prefixes.
Note that using this setting overrides prefixes added on thread creation and when a question thread is marked as solved or unsolved.

Added sidebars to pages listing threads with a specific prefix.

• Rename option "Show Prefix group above the thread list for filtering" to "Show prefixes above the thread list for filtering"
• Add option "Group prefixes above the thread list for filtering"
• When "Show Prefix group above the node list for filtering" is enabled, show prefix counts in the various drop downs
• Display the prefixes in the drop-down with their given style

Users with lots of prefixes can choose to group prefixes above the thread list for filtering, which can greatly reduce the clutter of having lots of prefixes individually displayed.

We had just one customer get server errors with Prefix Essentials because he was running with New Posts as the option (instead of Forums) for the Forums default page. This has been fixed.

Version 2.4.1 brings a new admin-customisable action button to expire prefixes.
It's a prefix-specific button that lives at the top of the thread, usable by people who have permission to edit the thread.
Admin can set the button text and confirmation message text.
When pressed by the user, it performs the expiry actions set by admin.
In our case on AVForums, we use it for users to more easily change the prefix in their classified advert threads. So the button is set to change the prefix, which is actually identical to editing the thread and changing the prefix there, but it's an easier UI.

Expiring prefixes with no set expiration date were expiring unexpectedly. This is fixed.

Fix for a server error when editing thread titles under certain circumstances.