Forces: Unify interface of forces for global and local forces

Currently, all transformation from world to body frame have to be done in force object's callback. We should split calculation of the actual force value/variation and its transformation into body frame, as this is something particular to the algorithms in use. As such, each force object provides its calculated force/variation and a flag, whether the force is global or local. Then, a global force will be converted to a local force in the backward and IDM/TIDM algorithms, whereas a local force will not be.