Multi Prefix 2.17.1

• Fix displaying prefixes in thread title

• Add missing hyphon between prefix and thread title in page title
• Add 5th paramater to template prefix() function 'appendTrailing' to control joining blob between title & prefix, if not set defaults to 4th argument 'append' glue

• Fix XF2.1.1+ compatibility, impacting some 3rd party add-ons

• Fix incorrect "There are no X matching your filters." when viewing an empty forum/XFRM category/etc

• Revert forcing an index hint when filtering by prefix as it produces very poor query plans on mariadb 10.3.x
• Remove support for XFRM v2.0.x, require XFRM v2.1.0+
• Compatibility fix for XF2.1.8

• Compatibility fix for single thread move not returning expected results

• Include prefix list when saying a prefix can't be removed
• Fix errors did not use the prefix's title, and instead had a phrase string
• Fix prefix not selecting when switching from a forum which only allows at most 1 prefix and a forum which allows more than 1 prefix
• Add "Strip unusable prefixes" option (default true) to control how individual content's move command handles moving where prefixes are not permitted to be used

• Improve extending XF js to be better compatible with other add-ons

• Fix " [E_NOTICE] Undefined index: prefix_id" when filtering by a prefixes for resources

• Fix pre-v1.6.0 upgrade code-path fro XF1 migrations
• Fix for "Rebuild Threads" job where the prefix list was not rebuilt correctly