* delete demo docs
* fix tree default value and dnd
* fix tree line and keys
* fix switcher icon and line
* fix line demo
* fix switcher
* add DirectoryTree demo
* fix draggable demo
* clean code
* clean code
* clean up the classmapper call
* update docs
* fix the docs
* fix comment
Co-authored-by: James Yeung <shunjiey@hotmail.com>
