GetHistoryForKey API with both start and end pointers

In 1.4.3 it was given a pointer to the first state of the chain by using GetHistoryForKey API.

Thanks to the iterator it was possible to navigate the chain from start to end.

In newer versions of HLF the iterator now starts from the end of the chain, so the last element.

My chaincode was done to navigate in a certain way and this breaks the mechanism. Also, to navigate from start to end, the only thing I can do is to reverse an array and this could be an intensive operation with long chains. 

I think that having both pointers would grant more chaincode possibilities to developers and is a really needed thing.