Update Jacobian tests for new initial conditions function

* Accurate initial conditions result in different Jacobians

* Most initial conditions used in the past were constant in space, so
  this doesn't invalidate any results etc.
In ODEProblem::set_initial_condition(...) loop over time in normal direction
Add a more robust make_boundaries_periodic(..) and use for a cube mesh
In parameter_sweep.py make args.ncores an int
Remove factor of 2 in time part of exact wave-like solution

There is an additional factor of two in the exact solution of one of
Jeong's papers (as compared to other places where the exact solution can
be found). It seems that this factor is wrong (at least without some
kind of additional forcing): the numerical solution matches well without
this factor but not with it.
Rename LLGBlockPreconditioner -> Magnetostatics...
In magnetostatic prec set the underlying llg prec by pointer

More general than just having some bools to use a few preset
preconditioners.
Add function to get RowColVal of a matrix
Add function to invert system with multiple rhs vectors
Add some more plots in parse.py
Remove uneeded test of cli blocking
Rename python test scripts in check_jacobians to match others