s chunk could be part of an end-of-line marker or not. This is the
context the function receives besides the chunk.  An updated version of
the context is returned after each new chunk.
</p>

<p class="parameters">
<tt>A</tt> is the translated version of <tt>D</tt>. <tt>C</tt> is the
ASCII value of the last character of the previous chunk, if it was a
candidate for line break, or 0 otherwise.
<tt>B</tt> is the same as <tt>C</tt>, but for the current
chunk. <tt>Marker</tt> gives the new end-of-line marker and