Export helper methods as named exports

[eysteinn13]

Issue: #650.
See #168 for a very similar PR on the Victory-Pie project.

• Export all methods individually as named exports, instead of export all helpers as a default export in the form of an object
• Reorder the method definitions to counter eslint's no-use-before-define errors. This makes the diff look mighty weird, so it might be easier to look at the individual commits' diff

We could not find a clean way to convert classes that were tested using sinon.stub() so we did not refactor them

[boygirl]

@eysteinn13 Thank you for taking on this chore. One change that needs to be made throughout:

things like

static getBaseProps = partialRight(getBaseProps.bind(getBaseProps), fallbackProps);

The bind is unnecessary now as you are no longer relying on context in the helpers (i.e. this.getCalculatedValues())

Another small change I would like to see:

In helpers that export several methods, I would like to see the exports all together at the bottom of the file like:

export default {
  getDomain, 
  getData, 
  getBaseProps
}

You can define them wherever you like in the file, but having the export statement at the bottom like that makes it much clearer what is being exported.

I will merge this work with those changes

[boygirl]

Unnecessary bind

[boygirl]

Also, a convention for next time: please use a branch with a descriptive name rather than submitting a PR from your master branch

[boygirl]

@eysteinn13 thank you for these changes :)