xF2 Add-on AndyB Prefix filter 1.4

Prefix filter v1.4 changes:

Added "Drop down" to options page.

Prefix filter v1.3 changes:

Now supports URL portion.

Prefix filter v1.2 changes:

Now shows prefixes in in a block for easy selection.

Prefix filter v1.1 changes:

Now compatible with XF 2.2.