Error CS0234: The type or namespace name `IActiveBuildTargetChanged' does not exist in the namespace `UnityEditor.Build'. Even after moving Editor folder.

Hi, I was searching for this error and I found [this](http://answers.unity3d.com/questions/1114080/the-type-or-namespace-name-unityeditor-could-not-b-2.html ) answer but it is not working. I moved Editor folder from StandardAssets/CrossPlatformInput/Scripts to StandardAssets folder and it is still throwing this error. I tried to put this folder in every single other folder but it is still not working. Should I put ALL scrips in Editor folder? I'm using Unity 5.6.2 on WIndows, and I imported whole CrossPlatformInput package and also couple of other standard packages.