Describe the bug

@StephenHodgson has written a documentation on how to add the MRTK to an existing repo via directory junction. This involves creating the junction as a subfolder of the assets data path. This breaks all appearances of hardcoded data paths:

(Paths I found)

• ControllerPopupWindow: 19: EditorWindowOptionsPath
• ThemeInspector: 1347: Shader.Find("MixedRealityToolkit/Standard")

To reproduce (first issue)

Steps to reproduce the behavior:

1. Add the MRKT via directory junction
2. Open a scene with MRTK and drill into the configuration Input -> Controllers -> Controller Definitions
3. Click one of the controller image buttons
4. See error

Expected behavior

No error no matter where the toolkit is placed in the project

Screenshots

If applicable, add screenshots to help explain your problem.

Your Setup (please complete the following information)

• Unity Version 2018.4.2f1
• MRTK Version 2 development_branch