org: tweak gnuplot package configuration

- remove variable org-disable-github-support, users can excluded it
the usual way (updated the documentation to mention this)
- lazy load gnuplot

layers/org/README.org

@@ -56,13 +56,8 @@ flavored markdown set the variable =org-enable-github-support= to =t=.
 Org-mode support the plotting of data within tables through [[http://www.gnuplot.info/][Gnuplot]] as
 demonstrated [[http://orgmode.org/worg/org-tutorials/org-plot.html][here]]; unfortunately, this is [[https://github.com/bruceravel/gnuplot-mode/issues/15][not terribly well supported]] on Windows
 at this stage.  It is possible to disable the configuration of gnuplot support
-through the variable =org-disable-gnuplot-support=.
-
-#+BEGIN_SRC emacs-lisp
-  (setq-default dotspacemacs-configuration-layers '(
-    (org :variables
-         org-disable-github-support t)))
-#+END_SRC
+as usual by adding the package =gnuplot= to your =dotspacemacs-excluded-packages=
+variable.
 
 ** Different bullets
 

layers/org/config.el

@@ -15,7 +15,4 @@
 (defvar org-enable-github-support nil
   "If non-nil Github related packages are configured.")
 
-(defvar org-disable-gnuplot-support nil
-  "If non-nil Gnuplot related packages are not configured.")
-
 (spacemacs|defvar-company-backends org-mode)

layers/org/packages.el

@@ -54,11 +54,9 @@
 
 (defun org/init-gnuplot ()
   (use-package gnuplot
-    :if (not org-disable-gnuplot-support)
-    :config
-    (progn
-      (evil-leader/set-key-for-mode 'org-mode
-        "mtp" 'org-plot/gnuplot))))
+    :defer t
+    :init (evil-leader/set-key-for-mode 'org-mode
+            "mtp" 'org-plot/gnuplot)))
 
 (defun org/init-org ()
   (use-package org