Dependencies for the examples

[anderslindho]

I noticed that numpy was a requirement to use this library.

I suppose that pyglet also could be added to this list, but since it technically only is used for the examples that part was less clear to me. I could add it to this MR as an optional feature if you'd like (through use of extras_requires).

[szabolcsdombi]

We use numpy in a lot of examples, but zengl itself does not depend on numpy. There are other libraries that can generate buffer data or simple file content is also sufficient. I really like using numpy and it is really well known.

The only dependency at the moment is glcontext which has no other open-source alternative yet.
ZenGL itself has 0 dependencies and it has a really small package size as well.
(this is important for the headless mode in a custom environment. also good for my upcoming raspberry pi test)

I like the idea of having extras_requires with glcontext and numpy at least, but it would be great to have all the dependencies of the examples.

A MR would be welcome for the extras_requires.
Thank you.

[szabolcsdombi]

Also pyglet is a dependency for most of the examples.

[anderslindho]

Like this or do you want glcontext as an install_requires?

Also, should I close this MR and add one with updated title+description or is this fine?

[szabolcsdombi]

This is fine, I update the readme soon to have this pip install offered too.

Is it pip install zengl[examples]?

[anderslindho]

Correct

[szabolcsdombi]

Thank you for your contribution