Add X3Dom export to get a easy webgl renderer

From a user voice request

add X3Dom export to get a easy webgl rendere

ParaView has already a nice X3D exporter. Would be very easy and useful if somebody would create an additional X3Dom exporter by adding some static lines to the X3D exporter. This would allow to render the data with WebGL in a web-page without a plugin. Example: http://x3dom.org/x3dom/example/x3dom_paraviewExport.xhtml