CLI2: Pseudo-args demoted to config settings

- When 'limit:N' is encountered, it is removed from the command line, and
  added as a config setting, equivalent to 'rc.limit:N'.
- This simplifieѕ subsequent command line parsing.

src/Context.cpp

@@ -595,7 +595,7 @@ void Context::getLimits (int& rows, int& lines)
   lines = 0;
 
   // This is an integer specified as a filter (limit:10).
-  std::string limit = cli2.getLimit ();
+  std::string limit = config.get ("limit");
   if (limit != "")
   {
     if (limit == "page")