Feature #1256 Follow-up

- Extended unit tests to cover 'add' failures.
- Removed whitespace at EOL.
- Updated ChangeLog, AUTHORS, NEWS.
- Updated taskrc.5.in.
- Updated CmdShow to allow new config settings.

src/commands/CmdShow.cpp

@@ -238,6 +238,7 @@ int CmdShow::execute (std::string& output)
           i->substr (0,  5) != "pull."                 &&
           i->substr (0,  6) != "merge."                &&
           i->substr (0,  4) != "uda."                  &&
+          i->substr (0,  4) != "default."              &&
           i->substr (0, 21) != "urgency.user.project." &&
           i->substr (0, 17) != "urgency.user.tag."     &&
           i->substr (0, 12) != "urgency.uda.")