Add tex listings snippets.

snippets/tex.snippets

@@ -263,3 +263,10 @@ snippet col2 two-column environment
 			${0}
 		\end{column}
 	\end{columns}
+# Code listings
+snippet lst
+	\begin{listing}[language=${1:language}]
+		${0}
+	\end{listing}
+snippet lsi
+	\lstinline|${1}| ${0}