Split 1D steady & unsteady scripts into functions.

* Perform two-grid and three-grid convergence for the steady case.
Compute convergence for 1-d unsteady case.

* Split script into functions.
* Add .swp to .gitignore.
Minor edits.

* Use an EPS of 1e-8.
* Do not print y_left.
* Edit .gitignore.
* Add FadlunEtAlSolver.py.
Add scripts to perform quadratic interpolation.

* Both steady and unsteady channel flow.
* Use 'Agg' for matplotlib to suppress GUI.