Add magit-svn plugin to git layer

contrib/git/README.md

@@ -12,6 +12,7 @@
         - [Github support](#github-support)
         - [Magit status fullscreen](#magit-status-fullscreen)
         - [Magit auto-complete](#magit-auto-complete)
+        - [Magit SVN plugin](#magit-svn-plugin)
         - [Git gutter](#git-gutter)
         - [Git](#git)
     - [Working with Git](#working-with-git)
@@ -85,6 +86,17 @@ function (the path should end up with a `/` to respect Emacs conventions):
 (setq magit-repo-dirs '("~/git/"))
 ```
 
+### Magit SVN plugin
+
+For convenience the magit SVN plugin can be activated directly in the Git
+layer by setting the variable `git-enable-magit-svn-plugin` to `t`.
+
+```elisp
+(defun dotspacemacs/init ()
+  (setq-default git-enable-magit-svn-plugin t)
+)
+```
+
 ### Git gutter
 
 In graphical environment `Spacemacs` will display [git-gutter][] icons in
@@ -159,7 +171,7 @@ Here are the often used bindings inside a `status buffer`:
 <kbd>L l</kbd>    | open `log buffer`
 <kbd>n</kbd>      | next search occurrence
 <kbd>C-n</kbd     | goto next magit section
-<kbd>N</kbd>      | previous search occurrence
+<kbd>N</kbd>      | previous search occurrence _or_ SVN sub-menu
 <kbd>P P</kbd>    | push
 <kbd>C-p</kbd     | goto previous magit section
 <kbd>q</kbd>      | quit

contrib/git/config.el

@@ -15,6 +15,9 @@
 (defvar git-enable-github-support nil
   "If non nil the Github packages and extensions are enabled.")
 
+(defvar git-enable-magit-svn-plugin nil
+  "If non nil `magit-svn' plugin is enabled.")
+
 (defvar git-magit-status-fullscreen nil
   "If non nil magit-status buffer is displayed in fullscreen.")
 

contrib/git/packages.el

@@ -32,6 +32,9 @@ which require an initialization must be listed explicitly in the list.")
           magit-gh-pulls
           )))
 
+(when git-enable-magit-svn-plugin
+    (push 'magit-svn git-packages))
+
 (if git-gutter-use-fringe
     (push 'git-gutter-fringe git-packages)
   (push 'git-gutter git-packages))
@@ -262,6 +265,15 @@ which require an initialization must be listed explicitly in the list.")
     :init (add-hook 'magit-mode-hook 'turn-on-magit-gitflow)
     :config (spacemacs|diminish magit-gitflow-mode "Flow")))
 
+(defun git/init-magit-svn ()
+  (use-package magit-svn
+    :commands turn-on-magit-svn
+    :init (add-hook 'magit-mode-hook 'turn-on-magit-svn)
+    :config
+    (progn
+      (evil-define-key 'emacs magit-status-mode-map
+        "N" 'magit-key-mode-popup-svn))))
+
 (defun git/init-smeargle ()
   (use-package smeargle
     :defer t