title: Create a NuGet package from a single C# project with 3 different build configurations
body: <p>I have a C# solution with single project (Project.csproj) which has 3 different build configurations each having different build directive (v1, v2, v3). The code inside the library changes depending upon these directives so you get 3 different DLLs after building. The reason for this is that this library is a wrapper for a 3rd party program DLL written in C. This program has 3 versions with some differences.</p>
  
  <p>The question is, how do I create a Nuget package for this? Should I create 3 different packages or is it possible to create just one (then the depending project would just use some directive to pick the right one)? Do I have to use a specifically tailored nuspec file or is to possible to simplify this with "nuget pack Project1.csproj ... some params" (so that i don't have to fill in the version, dependencies, etc. manually)?</p>
  
  <p>Thank you</p>