Add property to get the number of a page

app/src/main/java/eu/kanade/tachiyomi/data/download/Downloader.kt

@@ -302,7 +302,7 @@ class Downloader(private val context: Context, private val provider: DownloadPro
         if (page.imageUrl == null)
             return Observable.just(page)
 
-        val filename = String.format("%03d", page.index + 1)
+        val filename = String.format("%03d", page.number)
         val tmpFile = tmpDir.findFile("$filename.tmp")
 
         // Delete temp file if it exists.

app/src/main/java/eu/kanade/tachiyomi/data/source/model/Page.kt

@@ -12,6 +12,9 @@ class Page(
         @Transient var uri: Uri? = null
 ) : ProgressListener {
 
+    val number: Int
+        get() = index + 1
+
     @Transient lateinit var chapter: ReaderChapter
 
     @Transient @Volatile var status: Int = 0

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderActivity.kt

@@ -331,7 +331,7 @@ class ReaderActivity : BaseRxActivity<ReaderPresenter>() {
     fun onPageChanged(page: Page) {
         presenter.onPageChanged(page)
 
-        val pageNumber = page.index + 1
+        val pageNumber = page.number
         val pageCount = page.chapter.pages!!.size
         page_number.text = "$pageNumber/$pageCount"
         if (page_seekbar.rotation != 180f) {

app/src/main/java/eu/kanade/tachiyomi/ui/reader/ReaderPresenter.kt

@@ -579,7 +579,7 @@ class ReaderPresenter : BasePresenter<ReaderActivity>() {
                     // Build destination file.
                     val ext = MimeTypeMap.getSingleton().getExtensionFromMimeType(mime) ?: "jpg"
                     val filename = DiskUtil.buildValidFilename(
-                            "${manga.title} - ${chapter.name}") + " - ${page.index + 1}.$ext"
+                            "${manga.title} - ${chapter.name}") + " - ${page.number}.$ext"
                     val destFile = File(destDir, filename)
 
                     context.contentResolver.openInputStream(page.uri).use { input ->