*SetBodyInertia() - single body
Sets the mass properties of a body.
Syntax
*SetBodyInertia(body_name, mass, ixx, iyy, izz, 
                                           ixy, ixz, iyz)
    Arguments
- body_name
 - The variable name of an existing body.
 - mass
 - The mass of the body.
 - ixx, iyy, izz, ixy, ixz, iyz
 - The moments of inertia of the body.
 
Example
*Body(crank, 
"Crank", 
crank_cm)
*SetBodyInertia(crank, 
10, 10, 20, 30, 25, 35, 45)