Add MRT image support for Windows platform icons

MS platforms support the idea of MRT images where you refer to it as follows:

image.png

...but underneath there are actually different images per DPI...

image.scale-100.png
image.scale-140.png

... etc ...

The following must be improved to support MRT images
1. Scaled image versions are copied to platform images folder if defined in config.xml
2. Ensure all new image files from platform images folder are added to the project.