This commits allows for flexible choice of either ILU(0) or ILU(n) where n is a
dynamical parameter given in the parameter file. The default is 0 (as before).
In addition the relaxation parameter has been added to the parameter with the
default preserving the state from before.
Also, the default parameter for use_amg and use_bicgstab in the constructor of
CPRPrecondition have been removed.
fix parameter order for SeqILUn.
Merge pull request #252 from dr-robertk/PR/cprpreconditioner-more-flexible-choice-of-ilu

This commits allows for flexible choice of either ILU(0) or ILU(n).