Update .NET Core components, add tests for .Net Core library and .Net Core compiler, fix bugs and build process

This pull request should:

• highly improve the current version of .Net Core library and .Net Core compiler and quality of code
• improve and simplify build process
• improve documentation related to .Net Core library and compiler
• fix found bugs (some of bugs can be clarified like major - they are related to porting of protocols from Java version and can be present in C# library)
• add important unit tests for .Net Core library and .Net Core compiler
• add possibility to easy add unit tests for compiler for other languages