I have added `time_convergence.py`, a Python script based on `computer_order_of_accuracy.py` [here](https://github.com/su2code/VandV/blob/ad27cdf9391c9077f3ef14949e29c01be428b0d9/mms/fvm_navierstokes/compute_order_of_accuracy.py). This script loops over various different time marching schemes (e.g., `TIME_MARCHING = TIME_STEPPING`, `TIME_MARCHING = DUAL-TIME_STEPPING-1ST_ORDER`, `TIME_MARCHING = DUAL-TIME_STEPPING-2ND_ORDER`) for each of SU2's Navier Stokes Solvers (e.g., `FEM_NAVIER_STOKES` and `NAVIER_STOKES`) using different numerical methods (e.g., DG, JST, ROE+LIM, ROE, ROW+WLS).  Each case is evaluated at a different `TIME_STEP` size [1e-6 : 1e-10].