actually working custom lint passes

OpenRA.Mods.RA/Lint/LintBuildablePrerequisites.cs

@@ -0,0 +1,16 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using OpenRA.Traits;
+
+namespace OpenRA.Mods.RA
+{
+    class LintBuildablePrerequisites : ILintPass
+    {
+        public void Run(Action<string> emitError)
+        {
+            emitError("Hello World");
+        }
+    }
+}