Use nameof instead of hardcoded strings in reflection calls.

This helps improve the safety of code the uses reflection when methods may get renamed, and helps navigating code as the nameof will show up when searching for references to members.

OpenRA.Game/Scripting/ScriptContext.cs

@@ -287,7 +287,7 @@ namespace OpenRA.Scripting
 
 		Type[] FilterCommands(ActorInfo ai, Type[] knownCommands)
 		{
-			var method = typeof(ActorInfo).GetMethod("HasTraitInfo");
+			var method = typeof(ActorInfo).GetMethod(nameof(ActorInfo.HasTraitInfo));
 			return knownCommands.Where(c => ExtractRequiredTypes(c)
 				.All(t => (bool)method.MakeGenericMethod(t).Invoke(ai, NoArguments)))
 				.ToArray();