- Changed interface.
- Read tracerheads (tracer start locations) from file in compute_tof_from_files.
- Initialize tracerheads from wells in compute_tof.
Interface change: solver now requires a linear solver (for the multi-cell blocks only).
Implementation uses new private method assembleSingleCell(), that is a modified copy
of solveSingleCell(). Should refactor.
Deleted some unused code (or moved to opm-porsol), moved all code dealing with
time-of-flight to opm/core/tof, moved code for implicit transport solver to
opm/core/transport/implicit, spu_[im|ex]plicit.[ch] to opm/core/transport/minimal.