比例.js
满足设备的最佳比例。
一、API
// ** Params
// @el : {Element} the element
// @isLanscape : [OPTIONAL] {Boolean} by default is `false`(portrait)
// @radio : [OPTIONAL] {Number} the proportion of theShortSide/theLongSide，by default is `0.61`
// @maxWidth : [OPTIONAL] {Number} the max-width, by default is `640`
// @maxHeight : [OPTIONAL] {Number} the max-height, by default is `1008`
proportion ( el , is
