- ad_cache_memcache.module

    o asynchronously process changed nodes during cron runs
    o now support multiple hooks, so rename ad-cache-init to ad-cache-hook
 - ad_cache_memcache.inc
    o simplify code by using _debug_echo() when possible
    o preface debug calls with 'Memcache:' to make tracing more clear
    o replace ad_cache_memcache_init() with generic ad_cache_memcache_hook()
    o implement adserve_select hook