FEATURE: categories can require topics have a tag from a tag group

In a category's settings, the Tags tab has two new fields to
specify the number of tags that must be added to a topic
from a tag group. When creating a new topic, an error will be
shown to the user if the requirement isn't met.

app/controllers/categories_controller.rb

@@ -313,6 +313,8 @@ class CategoriesController < ApplicationController
         :navigate_to_first_post_after_read,
         :search_priority,
         :allow_global_tags,
+        :required_tag_group_name,
+        :min_tags_from_required_group,
         custom_fields: [params[:custom_fields].try(:keys)],
         permissions: [*p.try(:keys)],
         allowed_tags: [],