*Previous halfSitting had non-horizontal feet

*make talos_description into current package. remove other sub-packages
*Contains srdf file with feet specificities, halfSitting and disabled collision pairs
*Contains urdf file for loading simpler "collision" geometry in visual models.

*update half-sitting pose to a more dynamically stable one
*remove "Default" disabled collisions with leg_3_link and other common one
*remove other disabled collisions based on a more thorough Moveit sampling

*Defines the half-sitting position
*Defines common kinematic chains
*Disables "always in collision", "never in collision" and "adjacent" collision pairs after sampling of Configuration Space with Moveit.