Revision 274

Merge clcdrag and coefcdrag (following LMDZ revision 2232). Replace
local arrays by scalars. max(qsurf, 0), f_cdrag_ter, f_cdrag_oce in
clcdrag.  max(cepdu2, speed(i)**2) in coefcdrag, test zri > 0 instead
of >= 0. trm1 was unused in coefcdrag. No need for intermediary local
variable pref_local.