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");
+        }
+    }
+}

OpenRA.Mods.RA/OpenRA.Mods.RA.csproj

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="3.5" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
@@ -63,6 +63,7 @@
     <Compile Include="Air\FlyCircle.cs" />
     <Compile Include="Buildings\Sellable.cs" />
     <Compile Include="Effects\CashTick.cs" />
+    <Compile Include="Lint\LintBuildablePrerequisites.cs" />
     <Compile Include="ProductionBar.cs" />
     <Compile Include="Render\RenderEditorOnly.cs" />
     <Compile Include="SmokeTrailWhenDamaged.cs" />