New Post: Circular reference detector and package.config ordering

Hi dotnetjunky,

I started looking at porting the pull request over to 2.4.

There is indeed some conflict with the work to support packing referenced projects ( http://nuget.codeplex.com/SourceControl/network/forks/brugidou/nuget/contribution/3277 ).

It raises some questions:

• what should happen when the same package is referenced in different projects ?
  

I suggest the following:

• If the package reference version is different among the projects, then throw an error
• If version constraints are defined, intersect the constraints, and throw an error if the intersection is empty
• If target frameworks are different, throw an error
• A package reference is NOT a "development dependency" except if it so in all projects which refer to it (the values are AND-ed together).
  

It it all seems reasonable I'll go ahead with the implementation.
I will probably add some code in VersionUtility to help with intersecting version constraints, as it would now be needed in several places (once for 'aggregating' references version constraints, once for 'aggregating' dependency version constraints).