Finishing the tree from last time:
	We can make and join rings
	So we need to:
		Modify draw_branch so it uses make_end_ring and make_section
		Add actual branch curving to draw_branch
		Fix the texture coordinates so it doesn't look like bamboo

First:  Make draw_branch use our new functions
	It'll need a previous ring as a parameter
	Should we also have prev_pos?
		We *could* calculate the direction from the ring
		But since we already have it, let's not

Second:  Curves
	An observation:
		Branch curve varies a LOT
		Even in the same tree
	If I can't figure out the real term, I'll call our tree "subdividing"
		Oaks and Maples do this sometimes
		Pines and Red Alders don't
	Two basic principles about branch curving:
		Note:  "principle" here means "thing I saw a few times"
		Curves usually aren't abrupt
		Branches usually curve upward at the end
	Defining an S-curve:
		We need 4 points to interpolate between
		Interpolate, not calculate straight sections
			Weighting of a point increases as we get closer to it
	First point:  1/4 of branch distance, trajectory halfway bent
	Second point:  3/4 of branch distance, slightly offset away from ending

Third:  Texture coordinates
	draw_branch_section needs texture bounds
		Currently they're 0 and 1

Did any of that work?
	If so...leaves!

We need a make_leaf function
	Simple leaf or compound leaf?
	Can it be a polygon with a lot of vertices?
		I think Blender supports that
	Should they have stems?
	What angle are they at?
	We can trace some kind of leafish shape
		Oval?
		They can have a green texture

But where should the leaves be?
	Ends of branches?  Not really how trees are
	Attached to sufficiently-thin branches?
		Might look ok
		Smaller radius = higher chance of a leaf at each segment