[new feature] Toast support position prop (#244)

* [bugfix] Checkbox border render error in weixin browser

* [bugfix] TreeSelect dependency path error

* [bugfix] Swipe should clear autoplay timer when destroyed

* [bugfix] Optimize component dependency analyze when build style entry

* merge

* update yarn.lock

* update README.md

* update README.md

* update README.md

* update README.md

* update README.md

* [Doc] add more badges in README.md

* update README.md

* [bugfix] Address & Contact list style

* fix: contact test cases

* [bugfix] popup style missing when build style entry

* [bugfix] Search: onSearch event arguments missing

* [Doc] add demo pages

* update zan-doc@0.3.7

* fix: build entry error

* [Doc] add goods demo

* [bugfix] button primary background color

* [Doc] update doc detail

* [new feature] Coupon add 'showExchangeBar' prop && add empty style

* [new feature] Toast support `position` prop

* [new feature] Tabbar add 'info' prop

docs/examples-docs/zh-CN/toast.md

@@ -162,5 +162,6 @@ export default {
 |-----------|-----------|-----------|-------------|-------------|
 | type | 提示类型 | `String` | `text` | `loading` `success` `fail` `html` |
 | message | 内容 | `String` | `''` | - |
+| position | 位置 | `String` | `middle` | `top` `bottom` |
 | forbidClick | 禁止背景点击 | `Boolean` | `false` | - |
 | duration | 时长(ms) | `Number` | `3000` | 值为 0 时，toast 不会消失 |