EntityCache support

Taken from entity.api.php:

For entity_crud_hook_entity_info():

 * - entity cache: (optional) Whether entities should be cached using the cache
 *   system. Requires the entitycache module to be installed and enabled. As
 *   cached entities are only retrieved by id key, the cache would not apply to
 *   exportable entities retrieved by name key. If enabled, 'field cache' is
 *   obsolete and should be disabled. Defaults to FALSE.

There is also something in hook_entity_property_info():

 *     - clear: (optional) An array of property names, of which the cache should
 *       be cleared too once this property is updated. As a rule of thumb any
 *       duplicated properties should be avoided though.

So it seems very straightforward.