 <code>lyrics</code> class that parallels the structure and behavior of the other classes; added associated functions and generic method implementations.</li>
<li>Added <code>lyrics</code> argument support to <code>music</code> object construction and transformations.</li>
<li>Added lyrics argument to <code>track*</code> functions to support combining lyrics with an existing <code>phrase</code> object.</li>
<li>Added <code>render_music*</code> functions for making simple sheet music snippets directly from <