evolvefit does not rename PDFs

Created by: Zaharid

When I re-evolve a fit, I expect to get a usable LHAPDF grid that has a different name than the fit I started with. However the stricture is something like:

theory_163-190315_ern_nlo_xF2dot0xR0dot5_175_global $ ls  | head -n4
190315_ern_nlo_xF2dot0xR0dot5_175_global_0000.dat
190315_ern_nlo_xF2dot0xR0dot5_175_global_0001.dat
190315_ern_nlo_xF2dot0xR0dot5_175_global_0002.dat
190315_ern_nlo_xF2dot0xR0dot5_175_global_0003.dat

with all the files retaining the old name. This is inconvenient because either you have to overwrite the original PDF (which is a terrible idea) or you have to rename all the files by hand (which is easy to get wrong and cumbersome). Instead we should end up with a folder consistent with the filenames inside that is different from the original one.