Integrate X3D JSON into loader so it can load either JSON or XML files

[coderextreme]

The goal of this PR is to add support for X3D JSON Encoding

• Change1: Motivation: We wanted to be able to read X3D JSON. The chosen design approach was to convert the X3D JSON to existing proprietary JSON format inside the code, similar to how XML is converted to proprietary JSON
• Change2: Motivation: provide an example of the X3D JSON format. Many more examples are here: https://www.web3d.org/x3d/content/examples/X3dExampleArchivesJsonScenes.zip

[jonaskello]

Since this is a rather large PR it would be nice if you could provide a bullet point list in the main description of the PR summarising the changes that this PR will introduce. Also if you can add a motivation of why each of the changes were introduced that would be helpful when reviewing. Something like:

• Added support for JSON files. Motivation: JSON support is needed for XXX.
• Changed webpack to browserify. Motivation: ??
• Changed location of the bundle.js file. Motivation: ??
• etc.

[jonaskello]

I added a starting point for describing the PR in the main description. You can go ahead and edit this.