NuGet: support .NET Core & .NET Standards

The OpenGL.Net_VC15 solution includes project targeting .NET Core 1.1, .NET Core 2.0 and .NET Standard 2.0. The assemblies should be included in the NuGet package.

• Determine side effects for other derived NuGet packages (mainly .CoreProfile, .ES2Profile)
• Change .appveyor in order to use Visual Studio 2017 image (version 15.3)
• Determine .NET Standard 1.1 limitations
  • Cannot have library search path (multi-platform ANGLE support broken)
  • Memory.Set thrown NotImplementedException
• Determine .NET Standard 1.4 limitations
  • Cannot have library search path (multi-platform ANGLE support broken)
  • Memory.Set thrown NotImplementedException
• Determine .NET Standard 2.0 limitations
  • Memory.Set thrown NotImplementedException
• Determine .NET Core App 1.1 limitations
  • Cannot have library search path (multi-platform ANGLE support broken)
  • Memory.Set thrown NotImplementedException
  • Generic overrides cause boxing of blittable types (lack of __makeref)
  • Logging is not supported by metadata (lack of System.Xml)
  • No support for experimental GL extensions
  • EGL initialization depends on current working directory instead of assembly directory
• Determine .NET Core App 2.0 limitations
  • No support for experimental GL extensions
  • EGL initialization depends on current working directory instead of assembly directory

[ForNeVeR]

@luca-piccioni hey is there a reason why 0.7.1 NuGet package have .NET Core binaries, but 0.8.4 haven’t? Sorry but I can’t find any corresponding discussion.

[luca-piccioni]

Indeed we have a nuget package with .NET Core binaries,versioned as 0.7.1.