[GNU ELPA] Dash version 2.18.1

[ELPA update]

Version 2.18.1 of package Dash has just been released in GNU ELPA.
You can now find it in M-x package-list RET.

Dash describes itself as:
  A modern list library for Emacs

More at https://elpa.gnu.org/packages/dash.html

Recent NEWS:

# Dash NEWS -- history of user-visible changes

Copyright (C) 2012-2021 Free Software Foundation, Inc.

See the end of the file for license conditions.

## Change log

### From 2.18.0 to 2.18.1

- Fixed a regression from `2.17` as well as a long-standing bug in
  `--iterate`, which evaluated its arguments one too many times.  This
  in turn could lead to errors in `-flatten-n` when it tried
  flattening certain structures too far (#373).

### From 2.17 to 2.18

This release absorbs the now obsolete `dash-functional` version
`1.3.0` into `dash`, and brings the very old version of `dash` on GNU
ELPA up to date.

Package maintainers should replace all uses of `dash-functional`,
which will eventually be deleted, with `dash` version `2.18.0`.  For
more information on this, see:
https://github.com/magnars/dash.el/wiki/Obsoletion-of-dash-functional.el

- New function `-iota` for generating arithmetic sequences
  (@holomorph, #215).

- Calling `-list` with more than one argument is now deprecated.

- `-lambda` now accepts an empty argument list.

- New anaphoric macros `--reductions-from`, `--reductions`,
  `--reductions-r-from`, and `--reductions-r` corresponding to the
  analogous non-anaphoric functions.

- `-doto` threading now works as with `->`.

- New buffer-local minor mode `dash-fontify-mode` and globalized
  counterpart `global-dash-fontify-mode` for fontifying special Dash
  variables such as `it`, `it-index`, `acc`, etc.  The minor mode also
  fontifies calls to Dash macros in older Emacs versions which did not
  dynamically detect macro calls.

  This obsoletes the user option `dash-enable-fontlock` and the
  function `dash-enable-font-lock`, which is now an alias of
  `global-dash-fontify-mode`.

- New command `dash-register-info-lookup` for integration with `C-h S`
  (`info-lookup-symbol`).  This command allows Dash symbols to be
  looked up in the Dash manual just like Elisp symbols are looked up
  in the Elisp manual.  The command can be called directly when
  needed, or automatically from your `user-init-file`.  For example:

  ```el
  (with-eval-after-load 'info-look
    (dash-register-info-lookup))
  ```

- Dash is now listed under the standard [Customization
  
groups](https://gnu.org/software/emacs/manual/html_node/emacs/Customization-Groups.html)
  and [Finder
  
keywords](https://gnu.org/software/emacs/manual/html_node/emacs/Package-Keywords.html)
  `extensions` and `lisp`.

- The Dash manual is now licensed under the GNU Free Documentation
  License version 1.3.

- Various other bug fix, performance, byte-compilation, and
  documentation improvements.

### From 2.16 to 2.17

- Sped up `-uniq` by using hash-tables when possible (@cireu, #305).
- Fixed `-inits` to be non-destructive (@SwiftLawnGnome, #313).
- Fixed indent rules for `-some->` and family (@wbolster, #321).
- Added `-zip-lists` which always returns a list of proper lists, even for two
  input lists (see issue #135).

### From 2.15 to 2.16

- Added `--doto`, anaphoric version of `-doto` (#282).
- Aliased `-cons-pair-p` to `-cons-pair?` (#288).
- Generalized `-rotate` for `|N|` greater than the length of the list (@leungbk,
  #290).
- Added a mechanism to extend destructuring with custom matchers (@yyoncho,
  #277).

### From 2.14 to 2.15

This release brings new destructuring features, some new control flow
functions and performance optimizations.

- Added `-setq` with destructuring binding support similar to the `-let` family
  (#116).
- Added smarter key destructuring in `-let` and friends where variables are
  auto-derived from keys (#111).
- Allowed `-let` bindings without a source value form (#256).
- Added `-each-r` and `-each-r-while` (@doublep, #159).
- Added `-common-suffix` (@basil-conto, #263).
- Improved performance of folds (`-reduce` and friends) (@basil-conto, #264).

### From 2.13 to 2.14

This release retired Emacs 23 support.

- Added Edebug support for threading macros (@Wilfred).
- Added `-unzip`.
- Added support for `-first-item` ...
...