add support for structed bindings for Ogre::Vector

[ribbon-otter]

It would be nice to be able to write

auto [x,y,z] = myVector;

to conveniently pull myVector apart into its components for some algorithms. This pull request makes turns Ogre::Vector into a tuple-like (as defined in the C++ std library), so that structured binding is supported. Given that Ogre::Vector is a fixed length container, it is in many ways an specialized alternative to std::array, and std::array is also a tuple-like.

I invite feedback, particularly since Ogre::Vector is such a fundamental part of the Ogre project, and I am venturing into unfamiliar parts of the C++ language with this pull request.

[ribbon-otter]

looks like I forgot (and didn't find) how to run the tests that include trailing whitespace locally.

[paroj]

auto& [x,y,z] = myVector;
x = 1;

this should modify myVector.x, but currently will not work, right?

[paroj]

I did some tests:

for types that go through the VectorBase specialization things just work without this PR:

    Vector3 v;
    auto& [a,b,c] = v;
    a = 1;

the only problem are types that use the generic path:

    Vector3i v;
    auto& [a,b,c] = v.data;
    a = 1;

they need .data added

[paroj]

closing for now