Add undo-tree to the default Prelude packages

core/prelude-editor.el

@@ -344,6 +344,9 @@ indent yanked text (with prefix arg don't indent)."
 ;; enable Prelude's keybindings
 (prelude-global-mode t)
 
+;; sensible undo
+(global-undo-tree-mode)
+
 ;; enable winner-mode to manage window configurations
 (winner-mode +1)
 

core/prelude-packages.el

@@ -43,8 +43,8 @@
   '(ace-jump-mode ack-and-a-half elisp-slime-nav exec-path-from-shell
                   expand-region flycheck gist guru-mode helm helm-projectile
                   magit magithub melpa
-                  rainbow-mode solarized-theme volatile-highlights yasnippet
-                  zenburn-theme)
+                  rainbow-mode solarized-theme undo-tree
+                  volatile-highlights yasnippet zenburn-theme)
   "A list of packages to ensure are installed at launch.")
 
 (defun prelude-packages-installed-p ()