Not able to read symmetry objects from vsp file

[zala-2306]

Rotors defined by symmetry are not being imported from the VSP file. This file was generated for a hex-copter configuration, where three rotors were explicitly designed and the other three were created through symmetry. OpenCOPTER only recognizes three out of these six rotors. This issue persists even when the rotors are attached to the fuselage prior to applying symmetry.