XF2 Addons Search Improvements 2.19.1

A collection of improvements to XF's Enhanced Search and some for XenForo's default MySQL search

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

• Workaround XF2.2.13 does the search beforechecking it it can save it as a cached value, which can result in a query that is massively more complex than expected being sent to elasticsearch
  • This issue practically doesn't occur with stock XFES, but with additional search addons such as ElasticSearch Essentials this can generate unexpected errors