Add dali option to eclcc to allow cluster sizes to be extracted.

When eclcc resources a graph it currently assumes a default of 400 nodes in a cluster. For many clusters this is too pessimistic, and the correct value would generate graphs with larger subgraphs.

• Add a --daservers option to eclcc (and ecl) which allows eclcc to become a dali client. If enabled a callback would allow information about the cluster sizes to be retrieved from dali and used to optimize the queries.