Customizable spider core (1-30 arms)

n-arm spider arm core, inspired by tour's 6-arm design (Customisable Rubik's cube core, thing 1676041 by tour).

Several customization options are available through parameters (customizer), such as:
* The number of arms and orientation (Number_of_Arms):
All corner turning platonic and archimedean solids layouts will be available.
Currently 1,2,3,4,5,6,7abc, 8ab,12,14,20ab and 30 arm shapes implemented.
* Stem length (Length_of_Arm)
* Stem thickness (Diameter_of_arms),
* Core ball di