Add a embed mode as URL params which adds an overlay to avoid scroll hijacks

Gephi Lite can be embed in a iframe.
When going so in a web page which has vertical scroll gephi lite will capture scroll event to zoom in the graph when the mouse over the iframe. We could propose users who create such embeds a URL option which creates an overlay when mouse is over.
Overlay to be designed.

Start by locating the iframe embed handling, URL-parameter parsing, and the scroll or zoom event code. Define the overlay behavior and URL option before changing anything; done means an embedded graph can prevent scroll hijacking while preserving normal page scrolling outside the overlay.

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