Replace ColorRamp with HSLColor everywhere.

Fixes:
* Nuclear-purple color exploit.
* #3247.
* Removes a bunch of unnecessary color conversions every frame.

Caveats:
* The ramp range is now defined on the palette, so ramps can no longer be set per-player (may impact maps which define custom colors).
* It's no longer possible to perfectly recreate the original WW color ramps (I doubt we care).
* The old ColorRamp setting isn't migrated, so players will lose their color settings.

OpenRA.Mods.RA/Widgets/Logic/ObserverStatsLogic.cs

@@ -155,7 +155,7 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 			graph.GetSeries = () =>
 				players.Select(p => new LineGraphSeries(
 					p.PlayerName,
-					p.ColorRamp.GetColor(0),
+					p.Color.RGB,
 					(p.PlayerActor.TraitOrDefault<PlayerStatistics>() ?? new PlayerStatistics(p.PlayerActor)).EarnedSamples.Select(s => (float)s)
 					));
 
@@ -302,7 +302,7 @@ namespace OpenRA.Mods.RA.Widgets.Logic
 
 			var playerName = template.Get<LabelWidget>("PLAYER");
 			playerName.GetText = () => player.PlayerName + (player.WinState == WinState.Undefined ? "" : " (" + player.WinState + ")");
-			playerName.GetColor = () => player.ColorRamp.GetColor(0);
+			playerName.GetColor = () => player.Color.RGB;
 		}
 
 		static Color GetPowerColor(PowerState state)