Command Line Defaults

- Implemented support for rc.default.command.
- Implemented support for assumed info command.
- Implemented Arguments::inject_defaults to insert default arguments
  at just the right location.
- Corrected CmdCustom handling of limit:page.

src/Context.cpp

@@ -116,9 +116,12 @@ void Context::initialize (int argc, const char** argv)
   // Instantiate built-in column objects.
   Column::factory (columns);
 
-  // Finally categorize all arguments.
+  // Categorize all arguments one more time.
   args.categorize ();
 
+  // Handle default command and assumed 'info' command.
+  args.inject_defaults ();
+
   // TODO Instantiate extension command objects.
   // TODO Instantiate default command object.