Less clever newline detection

Assuming that if a file has a `\r`, its automatically a "mac format" is a bad assumption.

This leads to strange truncation issue like https://github.com/emacs-ess/ESS/blob/master/lisp/ess-julia.el.

Lets always split on known line breaks.

Also axed the `#mac_format?` all together. Sorta an effort to kill all the helpers under `BlobHelper`.

/cc @tnm