Deprecation of net46 support & move to grpc-dotnet

• Breaking changes:

  • Due to impending deprecation of .netFramework 4.6 (https://docs.microsoft.com/de-de/lifecycle/products/microsoft-net-framework) in 04/2022, the net46 build target was removed for all libraries. Build target is now netstandard2.0 and thus the lowest compatible .netFramework version is 4.6.1.
  • Build targets for executables (FileReaderWriterFactoryGRPCWrapper, OVFFileConverterGUI, PlausibilityChecker) were raised to net6. The previous target .netcoreapp2.1 is EOL since 08/2021.

• Improvements:

  • Due to the impending deprecation of the grpc.core nuget package (https://grpc.io/blog/grpc-csharp-future/) in 05/2022, the FileReaderWriterFactoryGRPCWrapper has been moved to the Grpc.AspNetCore.Server package and is now an aspnetcore webservice.

Improvements to process strategy definition and closed contours meta data

Improvements to process strategy definition and closed contours meta data in OVF definition
Added parameter pattern_hatch_length_in_mm for pattern definition.
Added STRIPES to pattern enum.
Added seperate ProcessStrategy fields for upskin and downskin to store ProcessStrategy parameter sets that are defined differently for upskin and downskin.
Clearified documentation of variables, resorted fields to indicate which parameters belong to the pattern definition.
Added parent_index and winding_number to closed contour to store the hierarchy of the contours.

Release v1.3.3 - CLI ASCIII support

Added support for ASCII formated CLI files to the CLI reader.

Release v1.3.2 - Improvements to file converter

Improvements and bugfixes to the file converter.
Also added a simple gui for the file converter with the OVFFileConverterGUI project.

API Extension: Added function ConvertAsyncAddParams to FileConverter.cs to inject parameters not present / supported in the source file into the target file.

API breaking - nothing.

Release of v1.2.2: Bugfix in OVF FileReader

OVF FileReader failed when a WorkPlane did not contain any vector blocks.

Pure bug-fix release, no API changes.

Release of v1.2.1: Fixed memory leaks in OVFFileReader

No changes to the API. Just fixed memory leaks resulting from streams not being properly disposed.

Release of v1.1.1: Update of OpenVectorFormat submodule.

Update of the OpenVectorFormat submodule to v1.3.

From the changelog:
API Changes:
Extension:

• Adds a name field in the ProcessStrategy and MarkingParams messages for a humand readable way to identify those.

Breaking: None

Release of v1.1.1: Minor fix for asp-file reader

ASP file reader now provides descriptive error message in exceptions and can handle empty lines in asp files now.

Release v1.1.2: ovf_lut.proto moved to submodule

With this release, the ovf_lut.proto moves to the OVF Definition repository (https://github.com/Digital-Production-Aachen/OpenVectorFormat) due to licensing reasons.

Now, third parties can implement their own .ovf file reader & writer libraries, without incorporating any LGPL code.

For users of the OpenVectorFormatTools, nothing changes. There were no changes to the api.

Release of v1.1.1: Update of protobuf dependency to 17.3

Updated protobuf version to 17.3.