取消父子任务不可重复的限制，支持循环任务触发等特殊场景；

doc/XXL-JOB官方文档.md

 - 23、新增任务运行模式 "GLUE模式(PHP) "，支持php脚本任务；
 - 24、执行器手动设置IP时取消绑定Host的操作，该IP仅供执行器注册使用；修复指定外网IP时无法绑定执行器Host的问题；
 - 25、任务失败重试优化：收敛并废弃现有失败重试策略，如调度失败、执行失败、状态码失败等，新增任务属性 "失败重试次数"，支持自定义失败重试次数，任务失败时将会根据该值进行失败重试；
-- 26、【迭代中】父子任务循环限制放开，支持特殊场景；
+- 26、取消父子任务不可重复的限制，支持循环任务触发等特殊场景；
 - 27、【迭代中】API服务支持动态参数；
 
 

xxl-job-admin/src/main/java/com/xxl/job/admin/service/impl/XxlJobServiceImpl.java

 						return new ReturnT<String>(ReturnT.FAIL_CODE,
 								MessageFormat.format((I18nUtil.getString("jobinfo_field_childJobId")+"({0})"+I18nUtil.getString("system_not_found")), childJobIdItem));
 					}
-					// avoid cycle relate
-					if (childJobInfo.getId() == jobInfo.getId()) {
-						return new ReturnT<String>(ReturnT.FAIL_CODE, MessageFormat.format(I18nUtil.getString("jobinfo_field_childJobId_limit"), childJobIdItem));
-					}
 				} else {
 					return new ReturnT<String>(ReturnT.FAIL_CODE,
 							MessageFormat.format((I18nUtil.getString("jobinfo_field_childJobId")+"({0})"+I18nUtil.getString("system_unvalid")), childJobIdItem));

xxl-job-admin/src/main/resources/i18n/message.properties

 jobinfo_field_alarmemail_placeholder=请输入报警邮件，多个邮件地址则逗号分隔
 jobinfo_field_executorRouteStrategy=路由策略
 jobinfo_field_childJobId=子任务ID
-jobinfo_field_childJobId_limit=子任务ID({0})不可与父任务重复
 jobinfo_field_childJobId_placeholder=请输入子任务的任务ID,如存在多个则逗号分隔
 jobinfo_field_executorBlockStrategy=阻塞处理策略
 jobinfo_field_executorFailRetryCount=失败重试次数

xxl-job-admin/src/main/resources/i18n/message_en.properties

 jobinfo_field_alarmemail_placeholder=Please enter alarm mail, if there are more than one comma separated
 jobinfo_field_executorRouteStrategy=Route Strategy
 jobinfo_field_childJobId=Child Job ID
-jobinfo_field_childJobId_limit=Child job ID({0}) cannot be duplicated with the parent job.
 jobinfo_field_childJobId_placeholder=Please enter the Child job ID, if there are more than one comma separated
 jobinfo_field_executorBlockStrategy=Block Strategy
 jobinfo_field_executorFailRetryCount=Fail Retry Count