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 note to find notebooks in wiki
add link to wiki
Fix lesson 2: removed extra m in Eq. (4)
Fix lesson 2—error in Euler scheme for phugoid eqs

The Delta t was in the wrong place for both equation (11) and (12).
Then these equations were repeated for no reason in the following
sub-heading.
Add linspace()->arange() challenge

and Pro tip to get the help pane
split cells to have headings in their own cell

plus add precision on convergence/consistency paragraph
Make text more precise when describing motion

especially when talking about the angles, we have pitch angle (positive
up), then glide angle in the force balance: a bit sloppy
turn around figure 3 for positive angle

and it's pitch angle, not glide angle
had to make a small change to reload fig

new figure not loading in nbviewer by simply replacing png file and
re-executing the markdown cell, yet git didn't detect a change in the
nb file?