Merge rflow_lst with cache_lst

[Teodor Ciuraru]

The idea is to lower the complexity of the Eddy API.

It might be possible combine the eddy$rflow_lst with eddy$cache_lst.

[Mike Badescu]

We need to keep them separate: there might be a case where we do not use memory cache, thus cache_lst = NULL, but we still need to keep track of rflow_lst