New fract4dc interface

[mindhells]

A new interface for the fract4dc has been created by introducing a new python extension type called controller.
The goal of this new interface is to avoid objects swinging in and out from fract4dc to python and the other way around all the time (which forces the need of having ugly interfaces and complicates the state handling).
No python scripts have been modified yet but only a new test has been created to demonstrate how to use it. Also the methods that would be deprecated by moving to this new interface have been marked in fract4d_module.cpp
In addition, a new folder examples has been created containing:

• python examples: demonstrating the minimum steps necessary to generate a mandelbrot image (using the new interface)
• C++ standalone examples: to explain how the engine (the pure C++ part of the fract4dc extension) works to do the same as the example above

The idea behind all this is to transfer all the knowledge gotten from analyzing and reorganizing the code to future developers.

[dragonmux]

Looks promising, but as example C++ code there are a few things that stand out to me.

[dragonmux]

My comments on malloc() usage still apply thanks to object lifetimes in the C++ VM, but your review of C compat head usage looks good otherwise

[mindhells]

I've applied most of the suggestions from @DX-MON to the examples (need to undo the const_cast though).
I think it makes sense to apply them to the extension codebase (sources under fract4d/c ... I like to call it "gnofract engine") itself. That would take some time so I would leave that out of the scope of this PR.

[dragonmux]

Looks much better, thank you. the rbga_t comment remains, but otherwise approved for merge.

Edit: re-checked, you did actually fix that.

[mindhells]

Hey @edyoung @DX-MON I don't have write access so, if you think the PR is ok to merge, please proceed

[edyoung]

As far as I can tell you should have the same access as a member of the 'fract4d' org. I don't mind granting write access - thought you already had it.