If you have selected some files, you intend to work on them. Also, this prompt
expects <kbd>c</kbd> / <kbd>s</kbd> which should cancel the next prompt in the
delete workflow. Rest of the three workflows are non-fatal.

Benefits of removing this option:
- code reduction
- one less step in the relevant workflows (more than one prompt feels dragged)

This prompt shows in the following workflows:
- delete: users have explicitly requested to prefer sel over current
- batch rename: key <kbd>^R</kbd> renames a single file
- archive: in most of the cases the user would want to archive the selection
- create sym/hard link: not a frequently used workflow (in general)

* Add -a option to generate a temporary NNN_FIFO

* Add documentation for -a option

* plugins/README.md: promote the use of -a

This obsoletes the global FIFO unlink trick, so I remove mentions of it.
@jarun update:

Polish -a

Replaces the following environment variables:
- NNN_USE_EDITOR
- NNN_IDLE_TIMEOUT

This reverts commit 278fcfdfc9.

- remove auto-stored session "@" on restore
- minor help update

This reverts commit cf388649b9.

- replace bools for internal non-persistent binary states with an uchar
- do not store path to session, derive from config path in tmp buffer
- program option to load session is not `-s`
- remove auto-stored session "@" on restore
- minor help update

* Improved completion support for files with spaces

Filenames with spaces, both generally and for session names, will now
complete as expected.

* Misc shell script improvements

See discussion on:
1cca9e4b72

* Initial commit of sessions implementation

* Reduce code duplication

* Move load session to program flag -e

* Fix context initialization problem when loading session

* Add pinned directory to session and reduce session file size

* Make load_session print an error if exists and few minor adjustments

* Refactor session's file structure

* Initialize required structures in load_session before loading

* Add load session dynamically, restore last session, and extra fixes

* Fix indentation

* Add sessions documentation to man page

* Update fish completions with sessions and make some improvements

* Move to single keybinding session management and add help info

* ESC when asked to insert session name behaves better

* Add sessions completion for bash

* Remove pinned dir from session and minor code refactors