Py5Shape's `get_children()` method should return `[]` when there are no children

[hx2A]

Both for empty GROUP shapes and non-GROUP shapes.

[hx2A]

From discussion #500 #499

[hx2A]

@villares , can you provide some example code that reproduces this bug?

I believe this is an easy fix, but when I was testing my fix, I realized my test code could not reproduce the problem when I didn't include my code change.

[villares]

The shapely experiment I posted (without an if guard) sometimes produced this I think (like when overlapping all circles). I'm away from the computer, but I'll try to remember providing some other shorter code to reproduce this!

[hx2A]

The shapely experiment I posted (without an if guard) sometimes produced this I think (like when overlapping all circles). I'm away from the computer, but I'll try to remember providing some other shorter code to reproduce this!

I thought of that, and already tried to reproduce it with that code. Then I realized I could try sometime simple:

def setup():
    s = py5.create_shape()
    print(s.get_children())

That did reproduced it. I'll merge the fix now.

[villares]

Ha! This is exactly what I wrote when I got back to the computer! Cool!