* Merge three files into one
* Merge two functions into one (*_bisection is gone)
* Move linear term out of the nonlinearity
* Use DirectionalConvexFunction from dune-tnnmg

problem_rhs_initial -> accelerationRHS

problem_rhs         -> velocityRHS
problem_iterate     -> velocityIterate
problem_AM          -> velocityMatrix

x/|x| isn't that big a deal and the logic was a gigantic mess