Importing backgrounds in Fred2 doesn't fully work.

Specifically, when trying to import the background from bp2-06, the end result is this:

However, when bp2-06 itself is loaded, the background box looks like this:

I'd not be surprised if the import background feature simply hasn't been updated to incorperate a lot of the slightly-more-recent features that FSO now has, but I'd be really happy if this could be fixed!

At first glance, missing is:

- Ambient Light
- Skybox, both model and direction
- number of stars
- lighting profile