this is a view that can drag sort buttons and merge buttons to a folder.
能够拖动排序菜单，和合并文件夹,删除按钮View。
效果类似桌面和招商手机银行app最爱菜单.

1:drag sort the buttons.拖动排序
2:drag button into a folder.把按钮拖进文件夹
3:drag button out of a folder.把按钮拖出文件夹
4:delete buttons in menu and folder.能够删除菜单和文件夹中的按钮
5:rename the folder.文件夹重命名.

1:make your data model extends com.panxiaohe.springboard.library.FavoritesItem;

2:make your adapter extends com.panxiaohe.springboard.library.SpringboardAdapter;

3:set the adapter to com.panxiaohe.springboard.library.MenuView;

4:springboardAdapter.onDataChange() will notice you data has change
  (when sortted change,moved in or out of folder,deleted button,changed folder name)
  you should save the change.
  
5:func setOnPageChangedListener(),setOnItemClickListener() is usefull too;

6:the attrs of the view :
    <attr name="row_count" format="integer"/>
    <attr name="column_count" format="integer"/>
    <attr name="divider_color" format="color"/>
    <attr name="divider_width" format="dimension"/>
    <attr name="default_folder_name" format="string|reference"/>
    <attr name="delete_icon" format="reference"/>
    <attr name="page_divider_width" format="dimension"/>
    <attr name="is_last_item_stable" format="boolean"/>
    <attr name="stable_header_count" format="integer"/>
    <attr name="folder_dialog_background" format="color|reference"/>
    <attr name="folder_view_background" format="color|reference"/>
    <attr name="folder_row_count" format="integer"/>
    <attr name="folder_column_count" format="integer"/>
    <attr name="folder_edittext_background" format="color|reference"/>
    <attr name="folder_edittext_textcolor" format="color|reference"/>
    <attr name="folder_edittext_textsize" format="dimension|reference"/>

this view is not well tested.