Line breaks in \highlight environment (+workaround).

As already mentioned in issue #51, the colorbox in highlighted text disallows linebreaks when using highlightmarkup=background. A workaround for this problem is to change the colorbox to use the highlight provided by the soul package:

\usepackage{color}
\usepackage{soul}
\renewcommand{\colorbox}[2]{\colorlet{tmpcolor}{#1}\sethlcolor{tmpcolor}\hl{#2}}
\usepackage{changes}

It would be great if this could be added as an option or even as the default highlight mode.