Returns the mass of any object (even non-PhysX) that is defined in the geometry LOD:
```
getGeometryMass _obj;
```
returns:
`Number: Mass`
Maybe can return the center of mass as well?
returns:
```
[Mass, CenterOfMass]
```
Use case: Projectiles (such as missiles) whose mass matters in their flight path, and maybe other stuff.