technically, EVERY file changed, since they have internal versions of 7.5.7
so i don't recommend just uploading according to the changes.txt file.
use a real tool, like beyond compare.. and merge any MODS that you may have from older code into the NEW files.
also, with a proper editor.. a search / replace in files is really easy...
there may be other files that aren't caught too.. that file can't be treated as gospel, nor should it have been that way in past releases either.
whenever i do an upgrade, the result is that EVERY file on the new install is properly a version 7.5.7 ( or newest ) version.
nothing old left behind.