Constrain camera pitch to +/- 90 degrees

refs #1960
Make viewTransform copy values, not reference to model transform

The viewTransform was copying the reference, so every time the model changed, it would clobber the view transform.
refs #1960
Create camera dynamically in scene.vwf.yaml when appropriate

It was added as a child in the .yaml, but since children are not inherited from prototypes, the application did not get the child camera.  Now it is created dynamically in initialize if the usersShareView property is set to true (otherwise users will create their own "navigable" object)
fixes #1970
Tidy code in physics/index.vwf.yaml

Moved scripts section of physics/index.vwf.yaml to end of document
refs #1960