Key enhancements in PHP 5.3.6 include:Upgraded bundled Sqlite3 to version 3.7.4.Upgraded bundled PCRE to version 8.11.Added ability to connect to HTTPS sites through proxy with basic authentication using stream_context/http/header/Proxy-Authorization.Added options to debug backtrace functions.Changed default value of ini directive serialize_precision from 100 to 17.Fixed Bug #53971 (isset()