## 2020-11-23
1. 去除导出YSelectCustomValue


## 2020-11-19
1. VALUE_TYPE => YSelectValueType
2. ICustomValue => YSelectCustomValue


## 2020-11-16
1. firstFetch  =>  shouldInitFetch
2. showAllOption => showDefaultOption
3. allOptionText => defaultOptionText
4. 增加参数 :
    1. apiDataKey，
    2. apiLabelKey，
    3. apiValueKey，
    4. defaultOptionValue，
    5. previewPlaceholder，
    6. shouldFetchWhenEmpty