Add proper CLRF-LF rules to .gitattributes.
Renormalize the bat files to LF in the repo and CRLF on disk.
Remove executable bit of files which shouldn't have it set
In some cases the license-identification header was missing,
so I added that as well. Replaced the remaining headers that
specifically identified "Versions 3.13.7 and higher".
Makefiles and the build system were deliberately excluded.