Nighty builds fixed

The Downloads page has been updated and the nightly builds (Windows and Linux!) are now generated by Github Actions. Now the build process is open for anyone to maintain, there’s a reference for package maintainers, and any mod and fork can make their own builds easily. Plus if something catastrophic happens, you’ll always have a mirror.

Some important changes to note:

• The Data Patch is now included with OpenXcom. You no longer need to worry about when to install it, update it, overwriting original files, etc. We’ve also moved it to Github so you can report any issues or changes there. If you’re compiling it yourself you still need to download it separately, but just stick it in your “bin” folder and you’re good to go.
• The Transifex translations are working again as well. If you need a version more recent than the one in the builds, just grab them from Github Actions.