Created UMM dump plugin

CommunityMapTool/build_guide.md

@@ -0,0 +1,10 @@
+1. Add the following to the `lib` folder from `[steam common dir]/Derail Valley/DerailValley_Data/Managed/UnityModManager`:
+        - `Assembly-CSharp.dll`
+        - `BezierCurves.dll`
+        - `UnityEngine.dll`
+        - `UnityEngine.UI.dll`
+        - `UnityEngine.InputLegacyModule.dll`
+        - `UnityEngine.IMGUIModule.dll`
+        - `UnityEngine.CoreModule.dll`
+        - `/UnityModManager/0Harmony.dll`
+        - `/UnityModManager/UnityModManager.dll`