Fix clang warnings, add clang to travis

Jan Breuer

2015-10-04 df3eeb1a9be519b5eaef18b8f7c2d7a201bf7b97

 README.md

@@ -45,6 +45,7 @@
<tr><td>String<td><code>"text"</code>, <code>'text'</code></tr>
<tr><td>Arbitrary block<td><code>#12AB</code></tr>
<tr><td>Program expression<td><code>(1)</code></tr>
<tr><td>Numeric list<td><code>(1,2:50,80)</code></tr>
<tr><td>Character data<td><code>MINimum</code>, <code>DEFault</code>, <code>INFinity</code></tr>
</table>