Revision 344

Replace pi / 180 by `deg_to_rad`

In procedure etat0, rename variable tsoil to ftsoil, which is the
corresponding name in the gcm program.

In `laplacien_gam`, replace call to scopy by array assignment.

Replace pi / 180 by `deg_to_rad` in `start_init_phys`.

Encapsulate diagcld1 and orolift in modules.

Avoid duplicated computation in `interfsurf_hq`.

Promote internal function fz of procedure soil to function of module
`soil_m`.  Use `new_unit` in procedure soil.