Added force_lock_settings=yes to "A New Land" and "Dark Forecast"

Without it, it was possible to uncheck "Use Map Settings" and make choices (such as factions, teams, turn limits) which can break the scenarios.

data/multiplayer/scenarios/2p_Dark_Forecast.cfg

@@ -10,6 +10,7 @@ Note: You need to use the default map settings for the scenario to work right."
     experience_modifier=100
     map_data="{multiplayer/maps/Dark_Forecast_basic.map}"
     victory_when_enemies_defeated=no
+    force_lock_settings=yes
 
     {DEFAULT_SCHEDULE_DAWN}
 

data/multiplayer/scenarios/4p_A_New_Land.cfg

@@ -6,6 +6,7 @@
     description= _ "This 4p survival scenario allows you to construct buildings and terraform the land. Use map settings. The recommended starting gold is 100."
     experience_modifier=70%
     turns=unlimited
+    force_lock_settings=yes
     define=MULTIPLAYER_A_NEW_LAND_LOAD
 
 #ifdef MULTIPLAYER_A_NEW_LAND_LOAD