Merge pull request #1441 from DafabHoid/fixdownloadercrashrelease

Downloader: Fix crash on loading unfinished downloads from .giga files (Fixup for release builds)

app/proguard-rules.pro

@@ -42,3 +42,9 @@
 -dontwarn javax.annotation.**
 # A resource is loaded with a relative path so the package of this class must be preserved.
 -keepnames class okhttp3.internal.publicsuffix.PublicSuffixDatabase
+-keepclassmembers class * implements java.io.Serializable {
+    static final long serialVersionUID;
+    !static !transient <fields>;
+    private void writeObject(java.io.ObjectOutputStream);
+    private void readObject(java.io.ObjectInputStream);
+}