Declares whether your application is willing to support right-to-left (RTL) layouts.If set to?true?and?targetSdkVersion?is set to 17 or higher, various RTL APIs will be activated and used by the system so your app can display RTL layouts. If set to?false?or if?targetSdkVersion?is set to 16 or lower, the RTL APIs will be ignored or will have no effect and your app will behave the same regardless of the layout direction associated to the user's Locale choice (your layouts will always be left-to-right).The default value of this attribute is?false.This attribute was added in API level 17.????????
聲明你是否支持從右到左（right-to-left?）的布局形式，如果設置true并且targetSdkVersion>=17,
各種各樣的RTL apis將會起作用臭脓，你的app會展示PTL布局
如果設置false或者targetSdkVersion<17（安卓4.2）缨该，RTL apis將不在起作用，即使選擇你的地區(qū)枉层，不管怎么樣，你的布局始終從左向右赐写。
默認值是false鸟蜡。
這個屬性在api17版本加入。
