x86_64 is used as a baseline: the "x86_64" entry, whatever status it has,
is transformed into "all", and then the other entries in ARCHITECTURES
either dropped or rearranged appropriately.
- Fix the license (it's GPL v2 not v1)
- Use the BeOS makefile instead of the Linux/SDL one and adjust the
dependencies
- Adjust some ifdefs to enable relevant code on Haiku
- Intentionally not added to the Deskbar menu: this can only be used by
loading files. There is nothing that can be done from the UI if not
started with a file.