[Robot Model] refactor the robot modelling framework

[tongtybj]

What is this

Improve the robot modelling framework.

Details

Create a new base class serving as the model for general multirotor (without articulated structure).

[tongtybj]

Refactor reuslt:

• Add a new base class for robot model called aerial_robot_model::RobotModel . This robot model is for common multirotors, such as quadrotor, that does have anly link structure.
• This new class also supports: a) multirotor with tillted rotors; b) multirotor with vectorable rotors.
• Class for robot model with link stucture aerial_robot_model::transformable::RobotModel is refactored to be derived from the base class of aerial_robot_model::RobotModel: aerial_robot_model::RobotModel -> aerial_robot_model::transformable::RobotModel.
• Derived class aerial_robot_model::transformable::RobotModel support any kind of reconfigurable model, such as hydrus, hydrus_xi, dragon, perching arm, etc.
• Plugin is necessary to be defined for any specific robot, since the above classes can not be directly loaded to our system ( we use pluginlib to load the robot model).

[tongtybj]

TODO

• [ ] Add a sample (ros package) about the common quadrotor @tongtybj . @HarukiKozukapenguin Please refactor your package with the instruciton from @tongtybj
• [ ] Add a sample (ros package) about the quadrotor with tilted rotors @sugihara-16. @sugihar-16 Please refactor your TRADY system, or you can ask itahara-kun to refactor his system.
• [ ] Add a sample (ros package) about the quadrotro with vectoring rotors @sugikazu75 @sugihara-16. Related to #526 #549 #550

[sugihara-16]

@tongtybj Although I may misunderstand your comment, regarding the third requirement, the sample package of quadrotor equipped with vectoring rotors has been already included in my new package.

Please check this with following command: roslaunch gimbalrotor bringup.launch realmachine:=false simulation:=true headless:=false airframe:=quad

[tongtybj]

@sugihara-16

I leave a comment in #549 .