Fixed value returns of classes bound as reference types in CLI backend.
Added P/Invoke helpers for unmanaged-unmanaged memory copies.
Managed tests now depend on the Runtime project.
Copy constructor P/Invokes are now generated in C# backend.
Simplified generated code dealing with hidden structure parameters.
Classes in AST now keep if they have non trivial copy constructors.
Simplified GetFunctionIdentifier and GetFunctionNativeIdentifier.
Fixed return of structures by value in C# backend similarly to the CLI backend by using copy constructors if the class has any non-trivial ones, or just copying memory directly if the class only has trivial ones.