refl/gray/after_onestep: fixed test for 2nd pass, fixed exin2,eyin2 evaluation, added test for powrfl<0

added branch for multiple passes (from nocommon rev142); fixed initial condition for second pass, new dispersion module for low density

partial changes uploaded by mistake in the previous revision. gray, interp_eqprof and reflections were in an inconsistent state

subroutine wall_refl moved in reflections module, rlim,zlim,nlim moved from interp_eqprof to reflections module

updated bfield routine, replacing btor/bpol; btotal passed explicitly to cniteq; equian partially modified (psinv passed as argument)

Hlambda function now evaluated from 1D spline in fjncl integration (mom. cons. CD model). Cleaned unused variables.

added modules graydata_flags, graydata_par, graydata_anequil, interp_eqprof, magsurf_data in nocommon branch