in reply to
OT: Does anyone know of a version control system that doesn't use separate files or a repo?
Version Control satisfies two needs, not one. Besides keeping track of previous versions, it also provides an archive, in case your file becomes damaged or lost. Consider the consequences of an additional space:
rm * .x
Having RCS,v files in the same directory or a subdirectory is a minimal protection. Having the archives in a separate file path limits your ability to wipe out your archive at the same time you delete a file. Having them in a separate partition makes it harder for the system to destroy both original and copy at the same time. Having them on a separate machine is even better. Considering a 2 TB drive costs $65 at Newegg, you can afford to partition part of a drive as a repository.
As Occam said: Entia non sunt multiplicanda praeter necessitatem.