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/commands/CmdCustom.cpp

@@ -149,7 +149,6 @@ int CmdCustom::execute (std::string& output)
   if (maxlines)
     maxlines -= (context.verbose ("blank") ? 1 : 0)
               + table_header
-              + context.headers.size ()
               + context.footnotes.size ()
               + 1;  // "X tasks shown ..."