Define a basic framework for robot kinematics and collision

[StephenYu-R]

[StephenYu-R]

Hard to script a graph, so split uml into following parts.

Robot3D/Skeleton3D
=======|------- Segment3D/Bone3D
============|-------- Joint info (Body connections and spring/damping constrains)
============|-------- Frame/mesh info from PhysicsBody3D)

Inheritance Chain:
Node3D <- CollisionBody3D <- PhysicsBody3D <- Segement3D
====================================|<- RigidBody3D
====================================|<- SoftBody3D
...

WIth frame info, one could implement kinematics and collisions in PhysicsBody3D and thus could be queried by Robot3D.

It's good to have a abstract layer of kinematics so that one can implement sorts of reused RobotTypes just by overriding kinematics as follows,

Robot3D <- Industrial6R
=======|<- Collaborative6R
=======|<- Palletizing4R

[StephenYu-R]

A numeric-based kinematics solver should be provided as a fundamental component before closed-form solvers are added as a plugin as the later will introduce parts of hardcodes to constrain general configurations.

[StephenYu-R]

A 3rd-party kinematics solver is also considered as dynamics solver will be applied when solving motion plans, such as jacobian, pseudo-jacobian, inverse-jacobian, etc.

[StephenYu-R]

RigidBody3D and Joint are only two basic types needed to compose a Robot3D so these two will be defined first.
We'll give up any abstract classes, such as CollisionBody3D and PhysicsBody3D.
Robot3D will be reconsidered after that.