Move meshobjects folder to show folder directory.

[AGFazio]

When using Import Previews/Models/Groups the default location for the moving head .obj files are in the xlights install directory. When importing from someone elses rgbeffects file these obj files are lost and don't show up in the layout.

I have set up a directory with the different vendors moving heads by type and quantity. This way users can easily set up movingheads in their layout as they are already pre-built. Video of process here: https://youtu.be/Q8A4ahjFZ6k

This would also be useful for users creating a 3D layout as the obj files for their layouts would be kept in the show folder.

Describe the solution you'd like
Posiibly move the meshobjects folder to the show directory and link to that folder. Or a way to default the location to the users xlights install directory.