Polylang Pro 3.6.5

* Pro: Use 'parse_query' rather than 'rest_{$type}_query' to filter REST requests.
* Pro: Filter the comments REST endpoint.
* Pro: Fix duplication of terms without language.
* Pro: Fix fatal error when Admin Columns is activated and no language is defined yet.
* Fix shortlink when using one subdomain or domain per language

* Pro: Fix conflict with JetThemesCore from Crocoblock
* Fix: better detection of REST requests when using plain permalinks
* Fix usage of deprecated action wpmu_new_blog in WP 5.1+
* Fix PHP notices with PHP 7.4

* Require PHP 5.6
* Fix PHP warning in WP 5.3