Revision 272

Add arguments psol and pref to clcdrag, in preparation of merge with
coefcdrag. Remove intent out arguments cdran and zri1 of coefcdrag,
not used. Make argument pref of coefcdrag optional, in preparation of
merge with clcdrag. Remove useless intermediary local variable zdphi
in coefcdrag. Remove unused local variable ri1 in stdlevvar.