1.2.3 Use WP_CACHE_KEY_SALT correctly.

#27 Sanitize WP_CACHE_KEY_SALT before using it in a filename.

1.2.2 avoid error-handling fault

#25 Fix error recovery defect. Props to Steven Sullivan.

1.2.1 -- correct defect in wp_cache_flush_runtime() implementation

1.2.1 #23 wp_cache_flush_runtime should not clear the persistent cache.

1.2.0 stability, statistics

1.2.0 Final FAQ tweaks.