Add keyb accelerators to file change & window state dialogs. Fixes #2928

src/atom-environment.coffee

@@ -933,8 +933,8 @@ class AtomEnvironment extends Model
           "Would you like to add the #{nouns} to this window, permanently discarding the saved state, " +
           "or open the #{nouns} in a new window, restoring the saved state?"
         buttons: [
-          'Open in new window and recover state'
-          'Add to this window and discard state'
+          '&Open in new window and recover state'
+          '&Add to this window and discard state'
         ]
       if btn is 0
         @open

src/pane.coffee

@@ -640,7 +640,7 @@ class Pane
       chosen = @applicationDelegate.confirm
         message: message
         detailedMessage: "Your changes will be lost if you close this item without saving."
-        buttons: [saveButtonText, "Cancel", "Don't Save"]
+        buttons: [saveButtonText, "Cancel", "&Don't Save"]
       switch chosen
         when 0 then saveFn(item, saveError)
         when 1 then false