Only process footnote links if component is mounted

[eatyourgreens]

• Checks for a root DOM node before querying the HTML content to find footnote links.
• Removes displayName.
• Replaces findDOMNode with a ref.

[eatyourgreens]

@simensta any objections if I merge this?

[simensta]

The code builds and the tests run successfully for me, but I am having trouble using npm link to test the package in Panoptes-Front-End. Is there another way to test the package in PFE?

[eatyourgreens]

Good question. I don't actually know how to test a build of markdownz, come to think of it.

[simensta]

I am now able to use npm link to test the package in PFE. However, I get the following error:

Uncaught Error: addComponentAsRefTo(...): Only a ReactOwner can have refs. 
You might be adding a ref to a component that was not created inside a component's `render` method,
or you have multiple copies of React loaded (details: https://fb.me/react-refs-must-have-owner).

[eatyourgreens]

npm link is working for me with a local copy of PFE so I'm not sure why that error is coming up. In the past, that error has been thrown when PFE and markdownz are using different versions of React. Both should be on 15.6.2. Does npm ls react show different versions installed for PFE?

npm install path might be a better alternative, if npm link isn't working.

npm install folder:

Install the package in the directory as a symlink in the current project. Its dependencies will be installed before it's linked. If sits inside the root of your project, its dependencies may be hoisted to the toplevel node_modules as they would for other types of dependencies.
https://docs.npmjs.com/cli/install

[simensta]

My npm link setup is finally working! 🎉 Thank you for your help!

I worked through the classification interface (submitting a classification and loading a new subject) looking for the errors mentioned here: zooniverse/Panoptes-Front-End#4324 (comment). I didn't see any DOM warnings or console warnings pertaining to markdown footnotes.

During this review, I noticed that the footnote feature doesn't display the footnote text. This is true of this branch as well as markdownz master. I'll create an issue so that can be addressed separately.

[eatyourgreens]

Published as 7.4.2.