[WIP] Glue types to enable iteration over just types (not values) with Hybrid::forEach()
This makes it possible to iterate over a list of types without the need to create objects of those types. Example:
using namespace Hybrid;
forEach(MetaTuple<void, NonConstructible, int>{}, [] (auto metaType) {
std::cout << className<typename decltype(metaType)::type>() << std::endl;
});
This comes from our internal module dune-react, where I use this to iterate over a list of grid manager types.
Planned merge: on-or-after 2017-02-23, unless there are significant negative comments.
[WIP] Investigate Carsten's proposals: !240 (merged).