system() & user input

["Andrew V. Samoilov" <kai cmail ru>]

There are some places in biultin editor, where systen() is called with
unchecked user input.

For example pipe_mail(), edit_sort_cmd() and edit_block_process_cmd() in 
edit/editcmd.c, but user input is not checked. It will be nice to use 
mc_doubleopen() there to prevent possible security and data loss issue 
there.

--
Regards,
Andrew V. Samoilov.