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?

test/att.t.cpp

@@ -34,7 +34,7 @@ Context context;
 ////////////////////////////////////////////////////////////////////////////////
 int main (int argc, char** argv)
 {
-  UnitTest t (121);
+  UnitTest t (118);
 
   Att a;
   t.notok (a.valid ("name"),              "Att::valid name           -> fail");