In this PR the Lax-Friedrichs flux is replaced by the upwind flux.
The Lax-Friedrichs flux function has been kept but the upwind flux is being used for the simulation.
The 1D Maxwell's equation upwind flux is also implemented and tested.
At several locations in the code, the math sphinx syntax was not correct, corrected it.
In this PR the Lax-Friedrichs flux is replaced by the upwind flux. The Lax-Friedrichs flux function has been kept but the upwind flux is being used for the simulation. The 1D Maxwell's equation upwind flux is also implemented and tested. At several locations in the code, the math sphinx syntax was not correct, corrected it.