lininterp 0.1.2

generic linear interpolation; should support dimension checking types ect by virtue of using fully generic intermediate values. Also includes various related functions: inv_lerp(x,x0,x1) f.lerp_between(y0,y1), x.lerp_points(x0,x1,y0,y1) , and y0..y1.lerp_by(x) (y0,y1).lerp_by(x))