Argument Parsing

- Obsoleted Command::exectute  'commandLine' argument.  It is worse
  than unnecessary, it is an uncategorized raw argument string, which
  is only really useful for the 'execute' command, which itself now
  calls Arguments::combine to reconstruct the command line string.

src/commands/CmdPrepend.cpp

@@ -44,7 +44,7 @@ CmdPrepend::CmdPrepend ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdPrepend::execute (const std::string&, std::string& output)
+int CmdPrepend::execute (std::string& output)
 {
   if (!context.task.has ("description"))
     throw std::string ("Additional text must be provided.");