Added CFD Python files
Updates for numerical-mooc

    * Deleted and changed references to CFD Python
    * Added license
    * Changed style
    * Changed imports to agreed convention
Trivial missing full stops.

Some semicolons to suppress output near plots.
Changed more references to CFD Python
Added solutions to spacetime module
Merge branch 'master' into spacetime_solution (update stylesheet)
replace all 26314 with eqn envir. to enable numbering
Merge pull request #8 from numerical-mooc/spacetime_solution_add_eqn_numbers

replace all $$ with eqn envir. to enable numbering
recreate shortcut for dt that keeps getting deleted
added section on Richardson extrapolation in 3rd lesson
Added discussion on Richardson extrapolation
Add new figure of forces on the glider

With trajectory pointing up, for a positive angle
Rewrote full-model formulation

Without magically eating constants like in the math notes. The factors
have physical significance!
Correct minor typos and grammar points.
Docstrings to numpydoc format.
Update the code to match the equations.

NOTE: should probably pick "real" numbers; currently chosen to match the original, non-dimensional equations.
Make python3 compatible.

This only needs minor changes to print statements including formatting;
should be backwards compatible with 2.7.
Include solutions for all exercises.

A lot of cut and paste so there is unnecessary code in many places.

Is it worth introducing the use of polyfit to measure the slope of the
lines in the loglog plot to measure convergence that way?
move 2nd order methods to separate notebook + small fixes
Create separate notebook for 2nd order methods and add helper function

01_04_helper_functions.py are loaded with %run magic in 2nd order
methods notebook -- it contains all the functions created in notebook 3
so we don't have to copy and re-run all of them in the 4th notebook.