improve Newton solver parameters
There were a couple of issues observed with the Newton solver:
AbsoluteLimitlower than 1e-8 is not observable in the (single precision) VTK output.
- ...but in mass conservation, see #39 (closed).
AbsoluteLimitis too high, the solver will not perform an iteration for small time steps and weak dynamics.
- We don't use
AbsoluteLimit = 1e-10
Reduction = 1e-4: To save time, allow a lower defect if the reduction is sufficient
ForceIteration = true: make sure that we don't skip dynamics