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.Cnc/Widgets/Logic/WorldTooltipLogic.cs

@@ -55,7 +55,7 @@ namespace OpenRA.Mods.Cnc.Widgets.Logic
 				{
 					flagRace = o.Country.Race;
 					ownerName = o.PlayerName;
-					ownerColor = o.ColorRamp.GetColor(0);
+					ownerColor = o.Color.RGB;
 					widget.Bounds.Height = doubleHeight;
 					widget.Bounds.Width = Math.Max(widget.Bounds.Width,
 						owner.Bounds.X + ownerFont.Measure(ownerName).X + 5);