Add support for "Shared Project" (*.shproj)

[tibel]

Currently SD5.0-beta4 can't load these projects. Also some management like (http://visualstudiogallery.msdn.microsoft.com/315c13a7-2787-4f57-bdf7-adae6ed54450) would be great.

[phrohdoh]

👍 please do when possible.
A tool of mine uses this but VS doesn't play nice (even with the available plugin) leaving MD/XS as the only tools to support this.