Update project to target .NET 4.5
Change output folder to AddIns\Samples\PInvoke
Add nuspec file for generating NuGet package for
AddIn Manager version 2
Third-party AddIns installed in SharpDevelop/AddIns are now visible in the AddInManager, only AddIns with 'addInManagerHidden="preinstalled"' stay hidden.
git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/branches/3.0@3806 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61