What this MR does / why does DuMux need it:
LocalAssembler classes to work with the newly introduced time step methods.
TODOS related to other WIP branches:
add support for cell-centered schemes, analytic assembly and further models (!2295)
make this work for staggered and multidomain (!2295, !2291 (merged), !2285 (merged))
Check if the public access to assembler and linear solver in
PDESolvercan be circumvented
TimeLevelinformation or if we should introduce different layers of grid variables that each store additional things. Like
FVGridVariablesor so. There is already an ongoing discussion about the grid variables inheritance hierarchy in !2285 (merged).
boundaryTypes()) to receive time information as well, such that time-dependent boundary conditions etc can be realized.