Merge branch '1490_multi_screens'

Merge branch '1490_multi_screens'

* 1490_multi_screens: (21 commits)
  Updated EN and RU man pages.
  Lock file is created and destroyed with full path.
  Implemented file locking in hex editor.
  Allow use file locking in various components of MC.
  Ask user before exit if there are opened screens in MC.
  SIGWINCH handling in suspended dialogs.
  Close dialogs during MC shutdown.
  Support of multiple editors and viewers.
  Added code names for parentheses, brackets and braces.
  MC Edit: column_highlighting flag is a member of WEdit struct.
  MCView: reimplemented messages and commands handling.
  Added type for MC viewer exit codes. Changed MC viewer run interface.
  Added function to get dialog title.
  Renamed current_dlg variable to top_dlg.
  Added modal flag to the dialog structure.
  Renamed dlg_id and parent fields of Widget structure.
  Reimplemented widget list in dialog using GList.
  Added dialog state (active, suspended, closed).
  Modified dialog initialization.
  Reimplemented dialogs stack using GList.
  ...