[org] Add ePUB support

CHANGELOG.develop

@@ -1745,6 +1745,7 @@ Other:
 - Added the org-mode keybindings to the org-journal major mode (thanks to Marty
   Buchaus)
 - Replace ox-reveal with org-re-reveal (thanks to Magnus Therning)
+- Add epub support (thanks to vishvanath45)
 **** Osx
 - Fixed OSX mapping issue (thanks to Joey Liu)
 - Added layer variables to customize modifier behaviors on macOS:

layers/+emacs/org/README.org

@@ -21,6 +21,7 @@
   - [[#org-brain-support][Org-brain support]]
   - [[#mode-line-support][Mode line support]]
   - [[#sticky-header-support][Sticky header support]]
+  - [[#epub-support][Epub support]]
 - [[#key-bindings][Key bindings]]
   - [[#starting-org-mode][Starting org-mode]]
   - [[#toggles][Toggles]]
@@ -301,6 +302,17 @@ To install sticky header support set the variable =org-enable-sticky-header= to
          org-enable-sticky-header t)))
 #+END_SRC
 
+** Epub support
+
+To install the Org exporter [[https://github.com/ofosos/ox-epub][ox-epub]] that generates e-book file format [[https://en.wikipedia.org/wiki/EPUB][epub]], set
+the variable =org-enable-epub-support= to =t=.
+
+#+BEGIN_SRC emacs-lisp
+  (setq-default dotspacemacs--configuration-layers
+                '((org :variables
+                       org-enable-epub-support t)))
+#+END_SRC
+
 * Key bindings
 ** Starting org-mode
 

layers/+emacs/org/config.el

@@ -40,3 +40,6 @@ used.")
 
 (defvar org-enable-trello-support nil
   "If non-nil org-trello is configured")
+
+(defvar org-enable-epub-support nil
+  "If non-nil org-epub is configured")

layers/+emacs/org/packages.el

@@ -31,6 +31,7 @@
         org-pomodoro
         org-present
         (org-projectile :requires projectile)
+        (ox-epub :toggle org-enable-epub-support)
         (ox-twbs :toggle org-enable-bootstrap-support)
         ;; use a for of ox-gfm to fix index generation
         (ox-gfm :location (recipe :fetcher github :repo "syl20bnr/ox-gfm")
@@ -644,6 +645,10 @@ Headline^^            Visit entry^^               Filter^^                    Da
       (org-projectile-per-project)
       (setq org-projectile-per-project-filepath org-projectile-file))))
 
+(defun org/pre-init-ox-epub ()
+  (spacemacs|use-package-add-hook org :post-config (require 'ox-epub)))
+(defun org/init-ox-epub ())
+
 (defun org/pre-init-ox-twbs ()
   (spacemacs|use-package-add-hook org :post-config (require 'ox-twbs)))
 (defun org/init-ox-twbs ())