Explain why we cant use a 0 initial condition
Set a default limit to the quadrature degree
Dont reset the quadrature degree after the solver.

Otherwise, the adjoint will be run with a different quadrature degree, causing
the Taylor tests to fail
Move the optimisation flags to the SW solver.

Running the test reduced from 5.20 min to 3.34 min
Remove more configuration code
Remanme SWSolver to CoupledSWSolver
Shorten some filenames
Rename some filenames
Move the functionals into their own directory
Remove the initial_condition module
Minor changes to the channel example
Move old examples to examples_old
Update documentation after recent changes
Start documenting the Orkney simulation example