Xon - Search Improvements 2.17.1

• Fix when logging debugging for some search queries would throw unexpectedly

• Enhanced specialized search with additional debug capabilities
• Update specialized search to support SearchOrder type
• Fix XF2.1 when using specialized search functionality (aka fix tag/user autocomplete with XF2.1)

• Improve 3rd party support for specialized search index support

• Add additional hookpoints for customizing "specialized search indexer" functionality
• On search results page, when searching a conversation(XF2.2)/direct message(XF2.3) display "with conversation/direct message"

• Search extensions API changes for better XF compatibility
  • XF2.3 compatibility fix for custom "SearchOrder" class
  • Simplify asSqlConstraint code (expected to always return an array)
  • AbstractConstraint::setMatchType needs to normalize to an int for MetadataConstraint::matchType

• Update installer to verify ElasticSearch index does not require rebuilding when this add-on is installed/updated/rebuilt
• Return 400 status code instead of 200 when the search query is wrong

• Compatibility fix for Username auto-complete using XFES and Tag auto-complete using XFES add-ons

• Fix guest user searches could be sent into a redirect loop depending on search criteria

• Restore XF2.1 support
• XF2.3 support
• Fix "[E_DEPRECATED] Use of "parent" in callables is deprecated" on search

• Add "Push thread prefix text into search" option (default true)
  • Supports ElasticSearch Essential's autocomplete
  • Requires manual rebuild of threads on changing this option