Don't change stack quantity when not editable

When displaying an inventory list in read-only mode, it was possible
to reset the quantity to 9999 if the value was higher than that by
clicking the field. This accidentally triggered the validations
applied when editing the field even though editing wasn't possible.

src/coffee/controllers/stack_controller.coffee

@@ -40,6 +40,8 @@ module.exports = class StackController extends BaseController
     # Event Methods ################################################################################
 
     onQuantityFieldBlur: ->
+        return unless @editable
+
         quantityText = @$quantityField.val().trim()
         if quantityText.length is 0
             quantity = @_priorValue
@@ -61,6 +63,8 @@ module.exports = class StackController extends BaseController
             @onChange()
 
     onQuantityFieldChanged: ->
+        return unless @editable
+
         quantityText = @$quantityField.val().trim()
         if not quantityText.match /^[0-9]*$/
             @$quantityField.addClass 'error', 0
@@ -78,6 +82,8 @@ module.exports = class StackController extends BaseController
             @$quantityField.blur()
 
     onQuantityKeyUp: (event)->
+        return unless @editable
+
         if event.which is Key.Return
             @$quantityField.blur()