- ad_cache_file.module

    o properly return ad configuration to not conflict with other cache
      types
 - ad_cache_file.inc
    o add additional debug output
 - adserve.inc
    o rename remaining instances of 'cache' to 'adcache' to avoid
      conflicts
 - ad_cache_memcache.module
 - ad_cache_memcache.inc
    o introduce new high-performance ad caching mechanism utilizing
      memcached