Remove \n from R.string.message_compose_reply_header_fmt

This string resource is used in two places -- both with and without the
linefeed at the end.  Instead of having a linefeed in the string and
having the code remove it if not needed, the linefeed is now omitted from
the string and the code adds it if needed.

Also, the line ending is changed from \n to \r\n.

Also, the string in the DE and FR locales had linefeeds at the start that
were removed so they match all the other locales.

(The string in the zh-rTW locale was left alone, since it had no
linefeeds.  It looks like that file has numerous instances where \n was
replaced with actual newlines, which is probably not correct.)