* feat(checker): new component checker

* test(checker): init checker test

* refactor(demo): add checker

* docs(checker): init checker docs

* refactor(checker): remove console

* test(checker): fix radio test

* fix(checker): radio & checkbox type active condition

* fix(checker): radio condition error

* refactor(example): checker router component path err

* test(checker): fix test

* add checker disabled

* add checker disabled document

* 修改checker文档

* 修改缩进

* 修改test

* docs(checkbox and checkbox-group): add events

* docs(components of form type): add input event documentation

* docs(rate component): modify documents

* docs(components of form type): modify events description

* docs(input): modify events description

fix(scroll): nested scroll bug

when inner element can't scroll

* feat(date-picker): add columnOrder prop

add columnOrder prop which can be used to change the display order in case where the order is not
'Year-Month-Day Hour-Minute-Second'

* docs(date-picker): add version for columnOrder

* docs(date-picker): fix the mistake in document of date-picker

change "Day" to "Date" in the expression of columnOrder prop

#427