TypeTree 2.6.0

• TypeTree has updated its minimum build toolchain requirements. You now need a compiler that is at least compatible with GCC 5 in C++14 mode and CMake 3.1.0.

• There is a new, simpler way of applying a functor to each tree node that keeps you from having to write a visitor by yourself, e.g.:

  int i = 0;
  forEachNode(tree, [](auto&&... node) {
    ++i;
  });

  Thanks to Carsten Gräser for contributing this feature!