Update render functionality:
    
        - Rename OPTIONNAM and OPTIONVAL varialbe names to ACTIONNAM and
          ACTIONVAL respectively.
    
        - Use the AsErrorLine output message style on error messages.
    
        - Rename render_getIdentityFileslist to render_getFilesFist
          function calls.
    
        - Add positional parameters interpretation using getopt(1) inside
          render_getFilesList function.
    
        - Change `--entry' to `--directory' option definition and
          `--filter' to reduce the amount of files processed inside the
          directory specified by `--directory'.