YAPF: Prevent user for configuring signal penalties to negative values

Warn if signal penalty polynomial goes negative, and clamp to non-negative

src/table/settings.ini

@@ -47,6 +47,7 @@ static bool ImprovedBreakdownsSettingChanged(int32 p1);
 static bool DayLengthChanged(int32 p1);
 static bool SimulatedWormholeSignalsChanged(int32 p1);
 static bool EnableSingleVehSharedOrderGuiChanged(int32 p1);
+static bool CheckYapfRailSignalPenalties(int32 p1);
 
 static bool UpdateClientName(int32 p1);
 static bool UpdateServerPassword(int32 p1);
@@ -3078,6 +3079,7 @@ def      = 10
 min      = 1
 max      = 100
 cat      = SC_EXPERT
+proc     = CheckYapfRailSignalPenalties
 
 [SDT_VAR]
 base     = GameSettings
@@ -3088,6 +3090,7 @@ def      = 500
 min      = -1000000
 max      = 1000000
 cat      = SC_EXPERT
+proc     = CheckYapfRailSignalPenalties
 
 [SDT_VAR]
 base     = GameSettings
@@ -3098,6 +3101,7 @@ def      = -100
 min      = -1000000
 max      = 1000000
 cat      = SC_EXPERT
+proc     = CheckYapfRailSignalPenalties
 
 [SDT_VAR]
 base     = GameSettings
@@ -3108,6 +3112,7 @@ def      = 5
 min      = -1000000
 max      = 1000000
 cat      = SC_EXPERT
+proc     = CheckYapfRailSignalPenalties
 
 [SDT_VAR]
 base     = GameSettings