Added sensors to objects;
Added grasp to robot nodes;
Extended RobotIO::RobotDescription;
Allow reloading of the robot visualization if RobotDescription::KinematicStructure is chosen

Generalize linear regression code to N-d, use explicit template initialization

See merge request Simox/simox!85

Linear regression 3d

See merge request Simox/simox!84

In this case, we just ignore the torque limit (it's just simulation, so what can go wrong :)

Feature/robot placement paper

See merge request Simox/simox!82