explicitly specify minimal cache factories to be cleared.
now we use kumofs as volatile memcached so we have no limit in key length and value size.
do not store _marker value in cache, especially for the value where loads(dumps(x)) != x.
cleanup code.
use the higest available pickle protocol version for better efficiency.
rename the title of portal_memcached/persistent_memcached_plugin.
remove non-used test code.
_getTypeBasedMethod now uses transactional variable cache, not erp5_content_long cache.