Model, LC: Add SQL export for lateral contribution.

src/Model/River.py

@@ -172,7 +172,7 @@ class River(Graph, SQLSubModel):
         RiverNode,
         RiverReach,
         BoundaryConditionList,
-        # LateralContributionList,
+        LateralContributionList,
         # InitialConditionsDict,
         # StricklersList,
         # SolverParametersList,
@@ -223,12 +223,17 @@ class River(Graph, SQLSubModel):
             execute,
             data
         )
+        new._lateral_contribution = LateralContributionList._sql_load(
+            execute,
+            data
+        )
 
         return new
 
     def _sql_save(self, execute, data = None):
         objs = (self._nodes + self._edges)
         objs.append(self._boundary_condition)
+        objs.append(self._lateral_contribution)
 
         self._save_submodel(execute, objs, data)
         return True