LISA orbitography gif animation

Function to build an animation of LISA space interferometer project path following Earth in the solar system.

For pedagogic / scientific diffusion purposes.

F5 in LISA_animation.m to run and create the animation file named 'LISA_orbitography.gif' that will appear in the same directory as you registered the .m file.

LISA spacecraft constellation draws an equilateral triangle, and each spacecraft path is shifted from its neighbors by 2/3 of a period (2*pi/3 = 4 months)

Old piece of code (updated for gif creation but not optimally factorized), but this is not the main thing here.