[Unity] How to build unsafe code

Step 1.
 (In the case of Visual Studio) Check "Project > Property > Build > Allow unsafe code"

Step 2.
 Make a file "Assets/smcs.rsp" and "Assets/gmcs.rsp" .
 Inside only '-unsafe' .

Step 3.
 Add 'unsafe' in Unity's "Edit > Project Settings > Player > Other Settings > Configuration > Scripting Define Symbols" .

Reference Sites
http://forum.unity3d.com/threads/how-do-i-enable-unsafe-code.210781/
https://github.com/Banbury/UnityPsdImporter/issues/9