Merge pull request #6 from gedoor/atbest

规范代码

app/src/main/java/io/legado/app/App.kt

@@ -4,12 +4,14 @@ import android.app.Application
 
 class App : Application() {
 
-    companion object{
+    companion object {
+        @JvmStatic
         lateinit var INSTANCE: App
+            private set
     }
 
     override fun onCreate() {
         super.onCreate()
         INSTANCE = this
     }
-}
+}