encourage users to list reducers in execution order

[YiningChen]

To make users more cognizant of reducers' execution order, encourage them to list the reducers in execution order. For example, given this code:

const input = {
  a: {
    text: 'Hello World'
  }
}

dataPoint.addEntities({
  'hash:example': {
    addValues: {
      b: { text: 'See You Later' }
    },
    mapKeys: {
      a: '$a.text',
      b: '$b.text',
    },
  }
})


dataPoint.transform('hash:example', input)

A user might expect { a: 'Hello World', b: 'See You Later' }
But instead they'll get { a: 'Hello World', b: { text: 'See You Later' } }

Therefore a warning should be given when reducers aren't in execution order

[acatl]

The only concern I have around this is that JS itself does not guarantee the order of keys, from my experience, Object key order is usually respected, at least in Node environments. where I have seen that this is not the case is when parsing from JSON to js.

Aside from this, I think this feature is a great idea and we should try to implement it.

[acatl]

closing because of #73