Remove newThread usages, it probably fixes random crashes

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

@@ -273,7 +273,7 @@ class DownloadManager(
                     page
                 }
                 // Retry 3 times, waiting 2, 4 and 8 seconds between attempts.
-                .retryWhen(RetryWithDelay(3, { (2 shl it - 1) * 1000 }))
+                .retryWhen(RetryWithDelay(3, { (2 shl it - 1) * 1000 }, Schedulers.trampoline()))
     }
 
     // Public method to get the image from the filesystem. It does NOT provide any way to download the image

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

@@ -14,7 +14,6 @@ import nucleus.factory.RequiresPresenter
 import rx.Observable
 import rx.Subscription
 import rx.android.schedulers.AndroidSchedulers
-import rx.schedulers.Schedulers
 import rx.subscriptions.CompositeSubscription
 import java.util.*
 import java.util.concurrent.TimeUnit
@@ -179,7 +178,7 @@ class DownloadFragment : BaseRxFragment<DownloadPresenter>() {
      * @param download the download to observe its progress.
      */
     private fun observeProgress(download: Download) {
-        val subscription = Observable.interval(50, TimeUnit.MILLISECONDS, Schedulers.newThread())
+        val subscription = Observable.interval(50, TimeUnit.MILLISECONDS)
                 // Get the sum of percentages for all the pages.
                 .flatMap {
                     Observable.from(download.pages)

app/src/main/java/eu/kanade/tachiyomi/ui/reader/viewer/pager/PagerReaderFragment.kt

@@ -21,7 +21,6 @@ import kotlinx.android.synthetic.main.item_pager_reader.*
 import rx.Observable
 import rx.Subscription
 import rx.android.schedulers.AndroidSchedulers
-import rx.schedulers.Schedulers
 import rx.subjects.PublishSubject
 import rx.subjects.SerializedSubject
 import java.io.File
@@ -168,7 +167,7 @@ class PagerReaderFragment : BaseFragment() {
         val currentValue = AtomicInteger(-1)
 
         progressSubscription?.unsubscribe()
-        progressSubscription = Observable.interval(100, TimeUnit.MILLISECONDS, Schedulers.newThread())
+        progressSubscription = Observable.interval(100, TimeUnit.MILLISECONDS)
                 .onBackpressureLatest()
                 .observeOn(AndroidSchedulers.mainThread())
                 .subscribe {

app/src/main/java/eu/kanade/tachiyomi/util/RetryWithDelay.kt

@@ -1,12 +1,15 @@
 package eu.kanade.tachiyomi.util
 
 import rx.Observable
+import rx.Scheduler
 import rx.functions.Func1
+import rx.schedulers.Schedulers
 import java.util.concurrent.TimeUnit.MILLISECONDS
 
 class RetryWithDelay(
         private val maxRetries: Int = 1,
-        private val retryStrategy: (Int) -> Int = { 1000 }
+        private val retryStrategy: (Int) -> Int = { 1000 },
+        private val scheduler: Scheduler = Schedulers.computation()
 ) : Func1<Observable<out Throwable>, Observable<*>> {
 
     private var retryCount = 0
@@ -14,7 +17,7 @@ class RetryWithDelay(
     override fun call(attempts: Observable<out Throwable>) = attempts.flatMap { error ->
         val count = ++retryCount
         if (count <= maxRetries) {
-            Observable.timer(retryStrategy(count).toLong(), MILLISECONDS)
+            Observable.timer(retryStrategy(count).toLong(), MILLISECONDS, scheduler)
         } else {
             Observable.error(error as Throwable)
         }