New design for all examples

Changes the overall design of all the XML3D examples.

Signed-off-by: Jan Sutter <jan.sutter@dfki.de>
Improved camera positions in OpenCTM and xflow-dataflow examples
Adapted paths in index.html
Autostart videos in AR-simple example
Removed self-closing tags from spotlight example
Fixed breadcrumb links
Merge branch 'new_design'