Use Mono.Cecil from nuget

BepInEx.Preloader/BepInEx.Preloader.csproj

@@ -31,8 +31,8 @@
     <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
   </PropertyGroup>
   <ItemGroup>
-    <Reference Include="Mono.Cecil">
-      <HintPath>..\lib\Mono.Cecil.dll</HintPath>
+    <Reference Include="Mono.Cecil, Version=0.10.3.0, Culture=neutral, PublicKeyToken=50cebf1cceb9d05e, processorArchitecture=MSIL">
+      <HintPath>..\packages\Mono.Cecil.0.10.3\lib\net35\Mono.Cecil.dll</HintPath>
     </Reference>
     <Reference Include="System" />
     <Reference Include="System.Core" />
@@ -61,6 +61,8 @@
       <Name>Harmony</Name>
     </ProjectReference>
   </ItemGroup>
-  <ItemGroup />
+  <ItemGroup>
+    <None Include="packages.config" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
 </Project>

BepInEx.Preloader/packages.config

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="Mono.Cecil" version="0.10.3" targetFramework="net35" />
+</packages>

BepInEx/BepInEx.csproj

@@ -36,8 +36,8 @@
     <CodeAnalysisRuleSet>MinimumRecommendedRules.ruleset</CodeAnalysisRuleSet>
   </PropertyGroup>
   <ItemGroup>
-    <Reference Include="Mono.Cecil">
-      <HintPath>..\lib\Mono.Cecil.dll</HintPath>
+    <Reference Include="Mono.Cecil, Version=0.10.3.0, Culture=neutral, PublicKeyToken=50cebf1cceb9d05e, processorArchitecture=MSIL">
+      <HintPath>..\packages\Mono.Cecil.0.10.3\lib\net35\Mono.Cecil.dll</HintPath>
     </Reference>
     <Reference Include="System" />
     <Reference Include="UnityEngine">
@@ -82,5 +82,8 @@
       <Name>BepInEx.Harmony</Name>
     </ProjectReference>
   </ItemGroup>
+  <ItemGroup>
+    <None Include="packages.config" />
+  </ItemGroup>
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
 </Project>

BepInEx/packages.config

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="Mono.Cecil" version="0.10.3" targetFramework="net35" />
+</packages>