[x3d-public] Interface hierarchy layout, other spec improvements

[Don Brutzman]

For X3D4 architecture specification in github:

1. Clause 4.4.2.3 Interface hierarchy (everyone's favorite section):

For glTF-related nodes, added layout whitespace for the "proposedDeletion" sections corresponding to "proposed" additions of intermediate abstract node types.

Seems more readable, it is much easier to see that there are no changes in the corresponding nodes themselves.  Michalis please check.

2. Interface hierarchy: also added PointProperties under X3DAppearanceChildNode, matching node definition and X3DUOM from Mantis 1252.

3. Interface hierarchy: added missing abstract type and nodes from Clause 42 Projective Texture Mapping (PTM):

   + X3DChildNode -+-

                   +- X3DTextureProjectorNode -+- TextureProjectorPerspective
                                               +- TextureProjectorParallel

Also added these to Node, abstract node type, and abstract interface index.

4. Layout component: no longer marked as deprecated.

5. Architecture (table of contents): improved descriptions.  Still need some work on Lighting and PBR synopses.

Dick, thanks for adding 4.0 column to versionContent.html page.  TODO, might you be able to add the three PTM nodes and PointProperties as well?

This will speed along our specification editors meeting.  Given that these changes were a solo effort, close scrutiny and refinements are especially welcome.

all the best, Don
-- 
Don Brutzman  Naval Postgraduate School, Code USW/Br       brutzman at nps.edu
Watkins 270,  MOVES Institute, Monterey CA 93943-5000 USA   +1.831.656.2149
X3D graphics, virtual worlds, navy robotics http://faculty.nps.edu/brutzman