[X3D-Public] X3D Schema, DTD corrections: finish Layer, Layout components

[Don Brutzman]

These improvements satisfactorily resolve some long-standing TODO items.

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X3D Schema update activity:

29 September 2012, brutzman
- (v3.2+) ScreenFontStyle added to TextChildContentModel and SceneGraphFragmentContentModel
- (v3.2+) LayoutLayer is an X3DLayerNode which is contained within the LayerSet content model
- (v3.2+) Layer, LayoutLayer and Viewport added to SceneGraphFragmentContentModel (since not in any ChildContentModel)
- (v3.1+) Corrected X3DFogObject containerField default to "children"

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X3D DTD update activity:

29 September 2012, brutzman
- (v3.2+) ScreenFontStyle added to FontStyleNodes
- (v3.2+) LayoutLayer is allowed within the LayerSet content model

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Tooltips have been added for Layout component:  Layout, LayoutGroup, LayoutLayer,
ScreenFontStyle, and ScreenGroup nodes.  Only Picking sensor component tooltips
remain to be added.  Reference links have been added to the bottom of each page
for versions 3.3, 3.2, 3.1 and 3.0 tooltips.

These validation cases can be tested using the X3D Validator service.
https://savage.nps.edu/X3dValidator

Also updated X3D Schema and DTD documentation.  Relevant links:
http://www.web3d.org/specifications/contents.html
http://www.web3d.org/specifications/X3dDoctypeDocumentation3.3.html
http://www.web3d.org/specifications/X3dSchemaDocumentation3.3/x3d-3.3.html
http://www.web3d.org/specifications/x3d-dtd-changelog.txt
http://www.web3d.org/specifications/x3d-schema-changelog.txt
http://www.web3d.org/specifications/x3d-schema-changelog.txt
http://www.web3d.org/specifications/X3dNodeInventoryComparison.xlsx
http://www.web3d.org/x3d/stylesheets/EncodingOfNodes.html

These and related links are maintained on the X3D Resources page:
http://www.web3d.org/x3d/content/examples/X3dResources.html#AuthoringSupport
http://www.web3d.org/x3d/content/examples/X3dResources.html#Tooltips

Review, comments, questions and improvements are 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