New script to splice DS into new RRD

[twinkiman]

I recently was refactoring my old cacti RRD and needed to splice a DS from one RRD into its own new RRD. I wasn't able to find any assistance available for it readily, so I wrote a perl script to do it. It can also rename a ds or delete a ds. In case anyone else needs it, it can be found at: https://github.com/jhg03a/modifyRRDs . Comments and commits are welcome.