1.6.0

This release is the first release supporting .NET Standard 2.0.
It's also splittet into several NuGet packages to broaden the usage scenarios.

• dotless.Core (the main stuff, supporting .NET Standard)
• dotless.AspNetHandler (ASP.NET Handler)
• [dotless] (https://www.nuget.org/packages/dotless/) (compatible to older pack ,contains Core and AspNetHandler)
• dotless.CLI (contains the command line application)