Make the symbolic links I used for the new perf suite relative

I had accidentally made these absolute symbolic links, so when they were run
somewhere that didn't have access to my files, errors were generated.

While I was there, I made the spectral norm .perfkeys file its own file instead
of a link from a different location, because that seemed likely to lead to less
surprising behavior in the future.
Merge pull request #1064 from lydia-duncan/resolveSymlinkPerfErrors3

Make the symbolic links I used for the new perf suite relative [ok'd in principle by mike]

I had accidentally made these absolute symbolic links, so when they were run
somewhere that didn't have access to my files, errors were generated.

While I was there, I made the spectral norm .perfkeys file its own file instead
of a link from a different location, because that seemed likely to lead to less
surprising behavior in the future.