fix: add properties initialisation in constructor instead of default property

Without this, the value of the properties are handles shared by all the instances of Scapula. So all the different scapula had the same CoordinateSystem and Plane instances, for example modifying SCase.shoudlers.right.auto.scapula.coordSys modified SCase.shoulders.left.manual.scapula.coordSys in the same way. Only one CoordinateSystem was instanciated and modified and both scapula were using it.