Added Namespace and SourceUri properties to the Element class. Fixes …

…Element Class Does Not Expose QualifiedName Or SourceUri #59.

Removed "Contributors" section from release notes.

Added a conformance note for three passing conformance tests in the "…

…Infer Calculated Value Consistency [Section 5.2.5.2 The CalculationArc Element]" category.

Update version to 2.1.0.17. Update references of .NET Standard 2.1 in…

… documentation to .NET 6.0.

Changed version number to 2.1.0.16 for Apr 2020 release.

Updated versioning to 2.1.0.15.

Updated version information to 2.1.0.14.

Updated NuGet package information to 2.1.0.13.

Updated version numbers to 2.1.0.12.

Edited project properties for version 2.1.0.11.