Add collision detection sample codes and doc

[AtsushiSakai]

Collision detection algorithm for real time processing is important for robotics.
So, these basic algorithm and knowledge should be added in this project.

Reference:
Amazon | Real-Time Collision Detection (The Morgan Kaufmann Series In Inteacive 3-D Technolagy) | Ericson, Christer | Software Development https://www.amazon.co.jp/-/en/Christer-Ericson/dp/1558607323

[idocode717]

Continuous Collision Detection (CCD)
python

Simplified CCD for moving spheres

def sphere_ccd(sphere1_pos, sphere1_vel, sphere1_radius,
sphere2_pos, sphere2_vel, sphere2_radius):
# Relative motion
rel_pos = sphere2_pos - sphere1_pos
rel_vel = sphere2_vel - sphere1_vel
combined_radius = sphere1_radius + sphere2_radius

# Solve quadratic for collision time
a = np.dot(rel_vel, rel_vel)
b = 2 * np.dot(rel_pos, rel_vel)
c = np.dot(rel_pos, rel_pos) - combined_radius**2

discriminant = b**2 - 4*a*c
if discriminant < 0:
    return float('inf')  # No collision

t = (-b - np.sqrt(discriminant)) / (2*a)
return max(0, t) if t >= 0 else float('inf')