NuGet AssimpNet.targets does not find native libraries

The file AssimpNet.targets file shipped with the NuGet package assumes that the Assimp-net NuGet package (containing the native Assimp[32|64].dll files) is located one directory up from the project file. See the `..\` in:

``` xml



```

This is a bad assumption since the NuGet packages are copied relative to the SOLUTION and not relative to the PROJECT. The assumption holds for simple example projects/solutions created with the VisualStudio project wizard. More complex solutions might reference projects not located one directory below the .sln file.

Start by inspecting the AssimpNet.targets file and its NativeAssimpLibs path, then compare that path with the package location in a solution whose projects are not directly below the solution file. Done means the targets file locates the native Assimp DLLs for both simple and more complex project layouts.

Written by the indexing model from the issue text.