I'll happily send you the diff if you want to code it in. But, the diff is about 44,000 lines, with most of it being interface changes that we can't use, audio code that we can't use, IA specific code that we can't use, HUD changes that we can't use, cross-platform issues that would need to be worked out, built on code that has since been removed from FS2_Open, and a large number of table changes that we can't use. Plus quite a few things that need to be done better so that they would be properly usable by the multitude of mods that we need to support.
But if you want it, it's all yours.
