Add ReaderModel#isInitialized

src/main/java/com/kdanmobile/reader/ReaderModel.kt

@@ -14,6 +14,7 @@ import com.kdanmobile.reader.screen.handler.*
 
 class ReaderModel {
     private var filename: String? = null
+    var isInitialized = false
     var password: String = ""
         private set
 
@@ -39,6 +40,7 @@ class ReaderModel {
         this.kmpdfFactory = kmpdfFactory
         this.filename = filename
         this.password = password
+        this.isInitialized = false
     }
 
     fun initKMPDFDocumentController() {