Gravity forces in assembly

[abhimadan]

There's no g parameter in assemble_forces or assemble_stiffness, so we can't use it to add gravity's contribution to the assembled force vector or Hessian. Are we expected to hardcode the standard acceleration into the appropriate functions?

[dilevin]

For this assignment your bunny should be in zero g (no gravity) so you can ignore the gravity force during assembly. You should still implement gravitational potential energy and the gradient so we can check the formulas though.