get_orientation_matrix, get_orientation_quaternion

[Simon-Steinmann]

Is your feature request related to a problem? Please describe.
The supervisor function 'get_orientation' currently returns a 1x9 list instead of a 3x3 list, which one would expect, since it represents the rotation matrix. Instead of changing this function, I suggest adding two new ones, as changing the existing function could break existing code.

Describe the solution you'd like
Add two new functions:
get_orientation_matrix() which returns a 3x3 list

get_orientation_quaternion() which returns a 1x4 list with the orientation expressed as quaternion. Preferably in [x, y, z, w] notation, as this is most commonly used in ROS and thus a majority of robotic projects and applications

[omichel]

@Simon-Steinmann: Please go ahead and open a pull request to propose this new feature. When introducing new API functions, we have to follow these guidelines to ensure the new functions are implemented in all languages, all platforms, are fully documented and tested. We will be happy to review your contribution.