Filters

- Implemented Command::filter_shortcut to detect when a filter begins
  with "status:pending" and skip the loading/parsing of completed.data.
- Removed obsolete att.t.cpp tests.
- Removed diagnostics from TDB2::TDB2 that were causing a segfault.
  I suppose there is no std::cout available during global ctors?

src/Context.cpp

@@ -266,9 +266,6 @@ int Context::dispatch (std::string &out)
     return c->execute (out);
   }
 
-  // TODO Need to invoke 'information' when a sequence/filter is present, but
-  //      no command is specified.
-
   return commands["help"]->execute (out);
 }