Square Axis for 3D plots

[acxz]

I've been working with 3D plots lately and it would be pretty nice to have an option of square3 similar to the 2D option of square as done here:

matplotplusplus/source/matplot/freestanding/axes_functions.cpp

Line 625 in 52d9e75

void axis(axes_handle ax, keyword_square_type) {

It seems it wouldn't be too hard to add, but I'm not sure if we would need an equal3 option as well.

Looking closer it seems so:

matplotplusplus/source/matplot/freestanding/axes_functions.cpp

Lines 574 to 582 in 52d9e75

	void axis(axes_handle ax, keyword_equal_type) {
	if (ax->children().empty()) {
	return;
	}
	float w = ax->width() * ax->parent()->width();
	float h = ax->height() * ax->parent()->height();
	auto [xmin, xmax, ymin, ymax] = ax->child_limits();
	double xrange = xmax - xmin;
	double yrange = ymax - ymin;

Any thoughts?

[alandefreitas]

Sounds like a good idea. We can just use the same square option and make this function behave a little differently if ax->is_3d().