Change Details

- improve a bit PHP Pitfalls to mention strlen() deprecation - mention is_string() benefits - mention phutil_nonempty_string() - link PHP Pitfalls from PHP Contributors Manual Ref T15190

- expand documentation about PHP Pitfalls to mention strlen() deprecation - mention is_string() - mention phutil_nonempty_string() - link from PHP Contributors Manual Ref T15190

- improve a bit- expand documentation about PHP Pitfalls to mention strlen() deprecation - mention is_string() benefits - mention phutil_nonempty_string() - link PHP Pitfalls from PHP Contributors Manual Ref T15190