Add setting for whether water floods from map edges

src/table/settings/settings.ini

@@ -3951,6 +3951,14 @@ pre_cb   = CheckFreeformEdges
 post_cb  = UpdateFreeformEdges
 cat      = SC_EXPERT
 
+[SDT_BOOL]
+var      = construction.flood_from_edges
+def      = true
+str      = STR_CONFIG_SETTING_FLOOD_FROM_EDGES
+strhelp  = STR_CONFIG_SETTING_FLOOD_FROM_EDGES_HELPTEXT
+cat      = SC_ADVANCED
+patxname = ""construction.flood_from_edges""
+
 [SDT_VAR]
 var      = game_creation.water_borders
 type     = SLE_UINT8