Fix dependency injection and use custom models extending DB ones

app/src/main/java/eu/kanade/tachiyomi/ui/download/DownloadAdapter.kt

@@ -35,7 +35,7 @@ class DownloadAdapter(private val context: Context) : FlexibleAdapter<DownloadHo
      * @return an identifier for the item.
      */
     override fun getItemId(position: Int): Long {
-        return getItem(position).chapter.id
+        return getItem(position).chapter.id!!
     }
 
     /**

app/src/main/java/eu/kanade/tachiyomi/ui/download/DownloadFragment.kt

@@ -262,7 +262,7 @@ class DownloadFragment : BaseRxFragment<DownloadPresenter>() {
      * @return the holder of the download or null if it's not bound.
      */
     private fun getHolder(download: Download): DownloadHolder? {
-        return recycler.findViewHolderForItemId(download.chapter.id) as? DownloadHolder
+        return recycler.findViewHolderForItemId(download.chapter.id!!) as? DownloadHolder
     }
 
     /**

app/src/main/java/eu/kanade/tachiyomi/ui/download/DownloadPresenter.kt

@@ -7,7 +7,7 @@ import eu.kanade.tachiyomi.data.download.model.DownloadQueue
 import eu.kanade.tachiyomi.ui.base.presenter.BasePresenter
 import rx.Observable
 import timber.log.Timber
-import javax.inject.Inject
+import uy.kohesive.injekt.injectLazy
 
 /**
  * Presenter of [DownloadFragment].
@@ -24,7 +24,7 @@ class DownloadPresenter : BasePresenter<DownloadFragment>() {
     /**
      * Download manager.
      */
-    @Inject lateinit var downloadManager: DownloadManager
+    val downloadManager: DownloadManager by injectLazy()
 
     /**
      * Property to get the queue from the download manager.