Fix Out Of Range Bug In BasicMLSequenceSet.

In the while loop, _sequences[sequenceIndex].Count should less equal than recordIndex, not less than. The origin version will cause exception when travel this dataset by

    for(var i=0;i < seq.Count; ++i){
        var tmp = seq[i];
    }
Merge pull request #54 from reyoung/patch-1

Fix Out Of Range Bug In BasicMLSequenceSet.