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
Changes to 1D linear convection notebook

    * Changed copyright information
    * Added welcome message to link to course
    * Removed links to youtube videos of CFD course
Edits on spacetime module

    * Modified copyright on all notebooks
    * Added welcome message linking the notebooks to the course
    * Deleted some leftover references to CFD Python
Python 3 compatible.

Also a minor typo.
Document the functions.
Python 3 compatible.

Minor additions to say what's going on.
Edits on spacetime_solution

    * Added discussion on numerical diffusion on notebook 1
    * Edits on first reference to stability in notebook 3
    * Added paragraph on stability for diffusion equation
spoof hash change to recover file following deletion
restore second order methods in dev branch
Add introductory paragraphs to notebook
Add more text on 2nd-order and RK methods
Second order method clean up
Clean up RK section of 2nd Order Methods notebook

    * Separated code following previous notebooks
    * Cleaned up parts of the code
    * Added comments on results for convergence and accuracy