Colors that span multiple lines should include a new span per line

[keithpitt]

Currently, the output renders like this:

some text <span class="c123">and this
this is colored</span>

The problem with this approach, is that if you wanted to wrap each line in a <div>, we've just broken our markup.

<div>some text <span class="c123">and this</div>
<div>this is colored</span></div>

If we have colors that span multiple lines, we should include <span> elements on each line, line so:

some text <span class="c123">and this</span>
<span class="c123">this is colored</span>