[x3d-public] Updated summary of my changes to X3Dv4, and reasoning "why do we need UnlitMaterial"

[Michalis Kamburelis]

Hi,

1. I have improved a "summary page" documenting my proposed changes for X3D v4:

  https://github.com/michaliskambi/x3d-tests/wiki/X3D-version-4:-New-features-of-materials,-lights-and-textures

That page is designed to be a quick introduction to all the changes.
It will also serve as a summary of my talk on next Friday (13th of
March) on Web3D teleconference.

2. I wrote a dedicated page about "Why do we need UnlitMaterial
node?". It's not so trivial question, and I gathered some arguments
before I decided it's the right course of action. It's all documented
on this page:

https://github.com/michaliskambi/x3d-tests/wiki/Why-is-UnlitMaterial-useful

Enjoy :),
Michalis