generic linear interpolation;
Should support dimension checking types etc by virtue of using fully generic intermediate values.
Also includes various related functions:
y = y0.lerp(&y1, t)
t=inv_lerp(&y,&y0,&y1)
t.lerp_between(&y0,&y1),
t.lerp_points(&x0,&x1, &y0,&y1) , and
(y0,y1).lerp_by(t))
where 't' is a dimensionless blending factor, x's and y's are types with potentially different dimensions.
y0.lerp(&y1,t).inv_lerp(&y0,&y1) == x
x.lerp_points(&x0,&x1, &y0,&y1) == y0.lerp(&y1,&x.inv_lerp(&x0,&x1))
Uses reference args, anticipating use with non trivial types eg vectors, image arrays, etc. However the factor is a simple value, anticipated to usually be f32
(also includes a helper 'pair_with()' for making tuples sequentially, e.g. x0.pair_with(&x1).lerp_by(t)