Use System XML for standalone builds to avoid strong name validation …

…error on Windows

 - Error is something like System.Security.SecurityException: Strong name validation failed

Assembly-CSharp.csproj

@@ -35,9 +35,6 @@
     <Reference Include="Antlr3.Runtime">
       <HintPath>DLLs\Antlr3.Runtime.dll</HintPath>
     </Reference>
-    <Reference Include="System.Xml">
-      <HintPath>DLLs\System.Xml.dll</HintPath>
-    </Reference>
     <Compile Include="MOD.Scripts.Core\MODXMLWrapper.cs" />
     <Compile Include="MOD.Scripts.AssetManager\MODAssetManager.cs" />
     <Compile Include="System.Runtime.Serialization\DataContractAttribute.cs" />
@@ -67,6 +64,9 @@
     <AssemblyName>Assembly-CSharp</AssemblyName>
   </PropertyGroup>
   <ItemGroup Condition="'$(Configuration)' != 'ScriptCompiler'">
+    <Reference Include="System.Xml">
+      <HintPath>DLLs\System.Xml.dll</HintPath>
+    </Reference>
     <Reference Include="UnityEngine">
       <HintPath>DLLs\UnityEngine.dll</HintPath>
     </Reference>
@@ -653,7 +653,7 @@
     <Optimize>true</Optimize>
   </PropertyGroup>
   <ItemGroup Condition="'$(Configuration)' == 'ScriptCompiler'">
-  <!-- Insert DLL or .cs files specific to standalone script compiler here -->
+    <Reference Include="System.Xml"/>
   </ItemGroup>
   <!-- End standalone script compiler items -->