v1.7-beta

Public Beta release of the .NET DllExport 1.7:

* NEW: Basic support for the netcore-based projects.
       Issues: #90, #67
       PR: #123

* CHANGED: Updated CoreCLR 3.0 IL Assembler 4.700.1
           https://github.com/3F/coreclr

* CHANGED: Updated Mono Cecil 0.11

* CHANGED: Updated MvsSln 2.5

* NOTE: You also need an updated manager to avoid problem
        when "Possible incorrect Sdk-based project types": PR #123
        https://github.com/3F/MvsSln/issues/23

        Use it from official 1.7-beta release:
        https://github.com/3F/DllExport/releases/tag/v1.7-beta
        https://www.nuget.org/packages/DllExport/1.7.0-beta

        Otherwise you need provide manually msbuild instance
        that can process modern Sdk-types due to modern VS/dotnet sdk
        dependencies for netcore-based projects.

        For example, through hMSBuild https://github.com/3F/hMSBuild
        ```
        DllExport ... -msb hMSBuild
        ```

* NOTE: To upgrade configured version to 1.7 beta:
        ```
            DllExport -action Upgrade -dxp-version 1.7.0-beta
        ```

* NOTE: Please don't use beta releases in production!

* NOTE: Please report about something here: https://github.com/3F/DllExport/issues

* KNOWN: You can finally get another System.Object in modified assembly:
         https://github.com/3F/DllExport/issues/90#issuecomment-546637702