Add layer for the Perl 6 Programming Language

This layer provides the following features for the Perl 6 Programming Language:

* Jump to definition & Code completion via [ctags-universal](https://github.com/universal-ctags/ctags)
* Syntax checking via [flycheck-perl6](https://github.com/hinrik/flycheck-perl6)
* Syntax highlighting & Syntax indentation via [perl6-mode](https://github.com/hinrik/perl6-mode)
* `META6.json` highlighting via [json-mode](https://github.com/joshwnj/json-mode)
* Provides evil text objects for:
    * double-angle-brackets
    * corner-brackets
    * single-quotation-marks
    * double-quotation-marks

See also #5019

layers/+lang/perl6/README.org

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+#+TITLE: perl6 layer
+
+# The maximum height of the logo should be 200 pixels.
+[[img/camelia-logo.png]]
+
+# TOC links should be GitHub style anchors.
+* Table of Contents                                        :TOC_4_gh:noexport:
+ - [[#description][Description]]
+ - [[#install][Install]]
+ - [[#key-bindings][Key bindings]]
+
+* Description
+This layer provides the following features for the Perl 6 Programming Language:
+  - Jump to definition & Code completion via [[https://github.com/universal-ctags/ctags][ctags-universal]]
+  - Syntax checking via [[https://github.com/hinrik/flycheck-perl6][flycheck-perl6]] and ~perl6 -c~
+  - Syntax highlighting & Syntax indentation via [[https://github.com/hinrik/perl6-mode][perl6-mode]]
+  - ~META6.json~ highlighting via [[https://github.com/joshwnj/json-mode][json-mode]]
+  - Provides evil text objects for: 
+    + double-angle-brackets
+    + corner-brackets
+    + single-quotation-marks
+    + double-quotation-marks
+
+
+* Install
+To use this configuration layer, add it to your =~/.spacemacs=. You will need to
+add =perl6= to the existing =dotspacemacs-configuration-layers= list in this
+file.
+
+It is highly recommended to install ctags-universal not ctags-exhuberant
+because it has support for Perl 6. You can use it to generate your ~TAGS~ file
+in your project directory like this:
+
+#+BEGIN_SRC
+ctags -e -Ra lib t/
+ctags -e -Ra --language-force=Perl6 bin/ $YOUR_PERL_PATH/share/perl6/site/sources/
+#+END_SRC
+
+* Key bindings
+
+| Key Binding | Description        |
+|-------------+--------------------|
+| ~SPC m g g~ | Jump to definition |

layers/+lang/perl6/config.el

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+(spacemacs|define-jump-handlers perl6-mode)

layers/+lang/perl6/packages.el

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+;;; packages.el --- perl6 layer packages file for Spacemacs.
+;;
+;; Copyright (c) 2012-2016 Sylvain Benner & Contributors
+;;
+;; Author:  Bahtiar `kalkin-`''Gadimov <bahtiar@gadimov.de>
+;; URL: https://github.com/syl20bnr/spacemacs
+;;
+;; This file is not part of GNU Emacs.
+;;
+;;; License: GPLv3
+
+(defvar perl6-packages
+  '(company
+    flycheck
+    flycheck-perl6
+    perl6-mode
+    json-mode
+    )
+)
+
+(defun perl6/post-init-company ()
+  (spacemacs|add-company-backends
+    :backends company-capf
+    :modes perl6-mode))
+
+(defun perl6/init-json-mode () (use-package json-mode :defer t))
+
+(defun perl6/init-perl6-mode()
+  (use-package perl6-mode
+    :defer t
+    :init
+    (progn
+      (add-to-list 'spacemacs-jump-handlers-perl6-mode 'evil-jump-to-tag)
+      (add-to-list 'auto-mode-alist '("/perl6/site/sources/" . perl6-mode))
+      (when (configuration-layer/package-usedp 'company)
+        (push 'company-capf company-backends-perl6-mode)
+        )
+      (spacemacs|define-text-object "«" "double-angle-bracket" "«" "»")
+      (spacemacs|define-text-object "｢" "corner-bracket" "｢" "｣")
+      (spacemacs|define-text-object "‘" "single-quotation-mark" "‘" "’")
+      (spacemacs|define-text-object "“" "double-quotation-mark" "“" "”")
+      )
+    )
+  )
+
+(defun perl6/init-flycheck-perl6 () (use-package flycheck-perl6 :ensure t :if
+                                      (configuration-layer/package-usedp 'flycheck)) )
+
+(defun perl6/post-init-flycheck () (spacemacs/add-flycheck-hook 'perl6-mode))
+
+;;; packages.el ends here