Enhancement - undo

- Removed obsolete undelete command.
- Removed obsolete undo command.
- Implemented new undo command as a call to the stubbed TDB::undo call.

src/TDB.cpp

@@ -488,6 +488,11 @@ int TDB::nextId ()
   return mId++;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+void TDB::undo ()
+{
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 FILE* TDB::openAndLock (const std::string& file)
 {