1. refactor: Model.extend support, (framework: MyObject,
   MyCollection, fn_extend_with_init)
2. add CategoryModel and CategoryListModel
3. getTermList->CategoryListModel,
   setSelectedCategory/getSelectedCategory->PostEditorModel
4. modify delPost: delete all orig Terms, use $.when(...)
escape post_name by 'escapeToUrl'
showHome after newPost, editPost, delPost
1. update Terms & TermRelationships ACL
2. route to home by goHome(), not by app_route.goHome() now
3. add ko.bindingHandlers.elem, not used yet
4. fix error: $.extend(this, postEditorModel.postModel); in
   fillFromPostEditorModel()
1. savePost(),delPost(): chain API calls in serial mode
   (multiple async call is chained by $.when)
2. showPost(): fetch post's terms so that edit post can be
   saved in single post view
3. fix bug: only post_excerpt is put into editor content
   when edit from page view
4. Admin siderbar: add "Check category count"