[Cgl] CGL Design - suggested CoinSnapshot

[J P Fasano]

> I think that CoinSnapshot is perfect

I think it needs a more descriptive name especially if it is going into
CoinUtils.

Perhaps:
 - CoinMipNodeSnapshot
 - CoinTreeNodeData
 - CoinNodeAttributes
 - CoinBranchParameters
 - or anything that better describes the data the class contains.

JP