Changeset 2575 for trunk/ORCHIDEE

1) Parameter SPLIT_DT was removed and replaced by DT_SECHIBA(time step of the sechiba component). The variable split is now calculated using the time step of the modele. Before it was the opposite (dt was calculated using split).

2) Name for parameter ROUTING_TIMESTEP changed to DT_ROUTING for consistency of parameter names.

3) Parameter DT_TURNOVER_TIME, the associated varaible dt_turnover_time and the getin for this parameter were removed because the variable is not used in the code.

See ticket #98