Finished step_po vanilla code... I think
Need to test it out, but first I'm committing and then see if the self
tests still passes.

Details:

modified:   lagrange_square/sq_lgr.cc
Tidied up code, made things consts.

deleted:    lagrange_square/sq_lgr_amg_test.qsub
Deleted run file from git, this is no longer needed.

modified:   lagrange_step/step_po.cc
Moved setup of boundary conditions of vanilla and parallel outflow into
separate functions.

modified:   rayheader.h
Fixed bullshit.