Rework mod enumeration / caching.

- Replaced ModMetadata.AllMods with Game.Mods.
- Store / reference mod Manifest instead of ModMetadata.
- Removes engine dependency on ModContent class.

OpenRA.Mods.Common/UtilityCommands/RemapShpCommand.cs

@@ -39,14 +39,14 @@ namespace OpenRA.Mods.Common.UtilityCommands
 				remap[i] = i;
 
 			var srcMod = args[1].Split(':')[0];
-			var srcModData = new ModData(srcMod);
+			var srcModData = new ModData(utility.Mods[srcMod], utility.Mods);
 			Game.ModData = srcModData;
 
 			var srcPaletteInfo = srcModData.DefaultRules.Actors["player"].TraitInfo<PlayerColorPaletteInfo>();
 			var srcRemapIndex = srcPaletteInfo.RemapIndex;
 
 			var destMod = args[2].Split(':')[0];
-			var destModData = new ModData(destMod);
+			var destModData = new ModData(utility.Mods[destMod], utility.Mods);
 			Game.ModData = destModData;
 			var destPaletteInfo = destModData.DefaultRules.Actors["player"].TraitInfo<PlayerColorPaletteInfo>();
 			var destRemapIndex = destPaletteInfo.RemapIndex;