+ add help in system nav.
 + add menu of help module.
 * rewrite index function.
 + add getFirstBook function.
 * add book field.
 + add translationg for directory.
 * add book field.
 * add book field.
 * adjust admin function if type is help.
 * add book field.
 * add book field.
 * name and code is notempty when create book.
 * use children instead of childs.
 * add the translation for book.
 + add code for book.
 * add the code for book.
 * use children instead of childs.
 * adjust code.
 + add translation for help module.
 * adjust createModuleMenu function.
 * add book field.
Merge branch 'master' of github.com:xirang/xirangeps

Conflicts:
	system/module/help/view/createbook.html.php
	system/module/nav/lang/zh-cn.php