defo reimplement this using just 3 `t_vec`s

[todo]

RT/src/algebra/shapes/shapes.h

Lines 47 to 51 in 950919a

	// TODO: defo reimplement this using just 3 `t_vec`s
	typedef struct s_triangle
	{
	t_plane plane;

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This issue was generated by todo based on a TODO comment in 950919a when #30 was merged. cc @emiflake.