Add detection of C++1y features (probably C++14)

I've added the most interesting features. I've skipped three features
that GCC and Clang will support:
  N3323  contextual conversion tweaks
  N3653  member initialisers and aggregates
  N3664  clarifying memory allocation

Of those, only N3653 brings a new syntax, so it could be added later.

Change-Id: I8314d81e028c9fb22052f73961c81cdc69c1461e
Reviewed-by: Robin Burchell <robin+qt@viroteck.net>
Reviewed-by: Kurt Pattyn <pattyn.kurt@gmail.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>