create_image_from_numpy() should support 'BGR' color channel ordering

[hx2A]

create_image_from_numpy() should support 'BGR' color channel ordering to facilitate using opencv with webcams. Otherwise, one needs to add [:, :, ::-1] to reverse the last dimension, and that's kind of weird and hard on beginners.

Adding this feature means adding it to set_np_pixels() in the pixels.py mixin.

https://py5coding.org/reference/sketch_create_image_from_numpy.html
https://py5coding.org/reference/sketch_set_np_pixels.html