[wt4] copied problem.par to problem.par.cylindrical (no changes)
[wt4] set up problem.par.cylindrical
[wt4] die in places that depends on geometry and geometry is not cartesian
[gravity] each standard gravity potential should check for supported geometry, e.g. grav_null should not die in cylindrical coords
[gravity] implemented GEO_RPZ in grav_ptmass_stiff
[wt4] all processes will have complete IC data
[wt4] some doxy