Merge

- Fixed merge, with an egregious hack for now, by creating zero-byte undo.data
  file.  This goes against the whole TDB2 philosophy, so it is temporary.
- Updated PUNCHLIST.
- Removed old tdb comment from CmdMerge.

src/commands/CmdMerge.cpp

@@ -97,7 +97,6 @@ int CmdMerge::execute (std::string& output)
        || (bAutopush) )
     {
       // TODO derive autopush uri from merge.default.uri? otherwise: change prompt above
-//      context.task.set ("description", uri._data);
 
       std::string out;
       context.commands["push"]->execute (out);