Construct and convert CartesianPose from rotation or transformation matrices

[eeberhard]

It would be convenient to be able to construct a CartesianPose object from a 4x4 transformation object. Similarly, it would be convenient to have a direct method get_transformation_matrix() or similar to return the pose as a 4x4 transformation matrix.

The 3x3 rotation matrix could be handled similarly, though for construction it would take either a 3vector for position or set position to 0.

This feature would make operations with other standard representations even easier.

[domire8]

1. get_transformation_matrix() already exists as function of CartesianState
2. Adding constructors like

   explicit CartesianPose(const std::string& name, const Eigen::Matrix4d& transformation_matrix, const std::string& reference = "world");
   

   is not as easy as it looks because it conflicts with existing constructors that Eigen is not able to resolve. We already have

   explicit CartesianPose(const std::string& name, const Eigen::Vector3d& position, const std::string& reference = "world");
   

   so then everything thats something like CartesianPose("A", 10 * Eigen::Vector3d::Random()) becomes ambiguous to the compiler.
3. One way to avoid this is to make a static method CartesianPose CartesianPose::from_transformation_matrix, if we want that

[eeberhard]

get_transformation_matrix() already exists as function of CartesianState

Since 4 years no less, how lovely!

Option 3 with a static method could be nice 👍