Dictionary versus Get next

[funazonki]

Seems like using a dictionary as the return result for GetRangeSlices makes it impossible for the client to do a sensible get next as the client has no way to know which KeySlice was the last one returned and so can't know which key to use as the start key for the next call.

Maybe GetRangeSlices should return IList<KeyValuePair<string, IList>> with the last entry guaranteed to be the last one returned by Cassandra.

Same issue with the other get functions that return a dictionary.