Rename data files to avoid ending in .py

[kslong]

The use of datafiles ending in .py is confusing. We have decided to standardize on .dat

[kslong]

So, I have created a new branch fixup for this. And I made most if not all of the necessary changes. There is a little script that I used fix_names.py for carrying out the changes.

There are still some data files that are not correctly named in a few passes. These are files which were not accessed by one of the master data files (or had names that been commented out). These will need to be fixed by hand, but one must check to make sure that they are not actually python scripts. There definitely are some of these in atomic80, e.g. extrapolate_log.py.

I corrected files ending with data, and with py, but occasionally another extension was use. It would be better if we were consistent.

I've tested the resulting data files with python but only superficially.

[kslong]

@Higginbottom @jhmatthews Hopefully you are following this issue, but in any event, when I looked in atomic80, I found two topbase files which have both a .dat and a .py version. git is sufficiently smart that did not allow me to copy the .py file over the .dat file since it was tracking both, but I don't really know what is intended today, but standard80 now points at the .dat file. Can one of you see what really was supposed to happen, hopefully whoever created the two versions in the first place. James, I decided not to fool with the atomic_macro directory. I'll let you do that.