Syphon server functionality (for usage in fulldome planetariums)

Syphon (http://syphon.v002.info/) is an open source Mac OS X technology that allows applications to share frames - full frame rate video or stills - with one another in realtime. Adding Syphon server functionality to Stellarium would allow planetarium operators to stream Stellarium footage in real time into dome-enabled VJ software packages, such as BlendyDomeVJ (http://www.blendydomevj.com/) or vDome (http://interactivedome.net/). In this way, Stellarium can be used also in multi-projector fulldome planetarium domes. This would promote the usage of Stellarium also in large-scale planetarium installations, where the already-implemented fisheye projection is not sufficient.