Add Exceptions to Class summary, update txtmark version

Updated the version of txtmark dependency to 0.8, as 0.7 is not available
from the specified repository. 0.8 can be obtained from maven central.

src/main/java/org/stfm/texdoclet/TeXDoclet.java

@@ -707,6 +707,7 @@ public class TeXDoclet extends Doclet {
 				}
 				tocForClasses("Interfaces", pkg.interfaces);
 				tocForClasses("Classes", pkg.classes);
+				tocForClasses("Exceptions", pkg.exceptions);
 				os.println("\\vskip .1in");
 				if (useHr) {
 					os.println("\\rule{\\hsize}{.7mm}");