* ReduceSum and ReduceSumSquare ONNX operations.

* Add new reduction ops.

- ReduceLogSum,
- ReduceLogSumExp,
- ReduceMax,
- ReduceMin,
- ReduceMean,
- ReduceProd.

* Add ReduceL1 and ReduceL2

* Utility generic functions generating monotonic sequences of values.

* Review comments: return AxisSet not std::vector

* Use common functions for generating monotonic sequence.

* Review comments.