* <update> better-scroll 1.9.1 + scroll + slide

* add activated and deactivated hook for keep-alive

* [add] dispatchTap

* add vertical loop for slide and make some opitmize to scroll

* <add>(date-picker)

* <add>(date-picker): example

* <add>(date-picker): value

* <update> value support Date type

* <update> event

* <add> test

* <update> test

* <update> expample

* <add> column config

* [update] column config

* [fix] min max

* [add] event param date

* [fix] max date

* [fix] memory

* [add] support Array type

* [fix] cascade column number reduce bug

* [fix] value change

* [update] example

* [add] doc

* [add] mixin: basic-picker + picker

* [update] example

* [add] test

* [update] doc + remove value-change event

* [update] variable name

* init logic

* form validate return valid value

* fix issue #123

* update(doc): location hash decode

* form basic

* fix ssr

* validator test

* form style

* ref form

* validator: rule to rules

* ref form

* validator: for to model

* update(doc&demo): add form

* validator: for to model

* eslint

* optimize form&validator

* handlerValidateRule condition check

* form: new-model to immediate-validate

* form field model to modelKey

* support json view

* fix form-item modelkey

* <add>(segment-picker): init

* <update>(segment-picker): select, cancel

* <add>(segment-picker): next, prev, title

* <add> change, selectIndex

* <update> v-bind object

* <add> test + update

* <update> test

* <update> example

* <add> comment

* <add>(create-api): $updateProps + (picker): watch selectIndex

* <delete> immediate

<add>(picker): support the change of column number when use setData

2. 在数据 dirty 情况下通过 refresh 和 destroy 来更新 wheels, 替代全部重新 create 方案

2. 列数减少时，去除多余的 pickerSelectedVal 和 pickerSelectedIndex

2. 过滤多余的 pickerSelectedVal

1. 列数增加: 增加的列对应的 scroll 未实例化无法滚动
2. 列数减少: pickerSelectedVal 保留了变化前选中的值