* `strftime()` has been replaced with a polyfill based on `DateTime`.
* Explicit type casts/assertions added where required by PHP 8.1
* `filter_var(…, FILTER_SANITIZE_STRING)` replaced with `strip_tags()`
or HTML entity encoding of quotation marks, depending on a guess of
what the intended "sanitization" was
* `http_build_query()` usage type mismatches fixed
* Removed usages of the `FILE_TEXT` constant
* To avoid breaking PHP 5.6 compatibility (function return types),
`e_session_db` no longer implements `SessionHandlerInterface`.
Instead, the alternative non-OOP invocation of
`session_set_save_handler()` is used instead to apply the session
handler.
* The shim for `strptime()` still calls the native function if available
but now suppresses the deprecation warning.
* `e_db_pdo` explicitly asks for `PDO::ATTR_STRINGIFY_FETCHES` to
maintain consistent behavior with past versions of PHP.
* `e_db_mysql` explicitly sets `mysqli_report(MYSQLI_REPORT_OFF)` to
maintain consistent behavior with past versions of PHP.
* Removed pointless random number generator seed from `banner` plugin
* Workaround for `COUNT(*)` SQL query in
`validatorClass::dbValidateArray()` without a proper API for avoiding
SQL injection
