Add validator that no custom scripts are present

[Insprill]

Custom scripts aren't supported, but map developers can still create scripts and export maps with them; they just won't work. We should explicitly force that no custom scripts are present.

[WhistleWiz]

What about custom scripts that are added with other mods? Those should technically work.

[Insprill]

We can add a dependency section to the MapInfo where you can put DLLs that automatically get added to UMM dependencies as well.