Fix wrong calculation radius for spline.

[Former user]

When we create spline we must calculate radius for arc with angle 90 degree. This radius doesn't calculate correctly.

Instead need find one leg of right triangle. This leg will be our radius.

Formula c=a/sqrt(2), where a - leg of the right triangle, c - hypotenuse of the right triangle.

[Former user]

Fixed issue #42.

→ <<cset a0458692431f>>