SWIG - C# std::tuple support

[Synergetik]

Added std::tuple swig interface definitions for C#.

It uses the same mechanics as std::function. So i split the common part into an own _swigforeach.i interface file. Durring this task i also improved the std::function generator a little bit.

The std::tuple can be used analog with std::function to define type defines, e.g:

%std_tuple(SerializationResult, la::avdecc::jsonSerializer::SerializationError, std::string);

The generated C# SerializationResult provides getter and setter methods to access the fields and a convenience method to Deconstruct it into C# tuples, example usage:

var (error, result) = controller.serializeAllControlledEntitiesAsJson("myfile", flags, "", true);

[christophe-calmejane]

Merged, thanks Vitalij