break_lines uses LFs, not CRLFs like you might expect (since it's
designed for email-related use), but we can't change that now since
the caller has to allocate the output buffer and so the
number-of-bytes-output is part of the ABI. So, just document that.
https://bugzilla.gnome.org/show_bug.cgi?id=668158
* @break_lines is typically used when putting base64-encoded data in emails.
* It breaks the lines at 72 columns instead of putting all of the text on
* the same line. This avoids problems with long lines in the email system.
+ * Note however that it breaks the lines with <literal>LF</literal>
+ * characters, not <literal>CR LF</literal> sequences, so the result cannot
+ * be passed directly to SMTP or certain other protocols.
*
* Return value: The number of bytes of output that was written
*