koreader: Enable auto update

And upgrade to v2019.04

metadata/org.koreader.launcher.yml

@@ -43,11 +43,31 @@ Builds:
       - ANDROID_FLAVOR=fdroid ./kodev release android
     ndk: r15c
 
+  - versionName: v2019.04
+    versionCode: 6696
+    commit: v2019.04
+    submodules: true
+    sudo:
+      - apt-get update || apt-get update
+      - apt-get install -y gcc-multilib luarocks p7zip-full
+    output: koreader-android-*.apk
+    rm:
+      - platform/ubuntu-touch/
+      - platform/win32/
+    scandelete:
+      - base/thirdparty/
+    build:
+      - NDK=$$NDK$$
+      - SDK=$$SDK$$
+      - ANDROID_FLAVOR=fdroid ./kodev release android
+    ndk: r15c
+
 MaintainerNotes: The app is English-only for now, because it requires fetching the
     translations from Transifex (see [https://github.com/koreader/koreader/tree/master/l10n
     here]) and we can not do this without credentials.
 
-AutoUpdateMode: None
-UpdateCheckMode: None
-CurrentVersion: v2019.03.1
-CurrentVersionCode: 6623
+AutoUpdateMode: Version %v
+UpdateCheckMode: HTTP
+UpdateCheckData: https://ota.koreader.rocks/koreader-android-fdroid-latest|(\d+)$|.|(v.*)
+CurrentVersion: v2019.04
+CurrentVersionCode: 6696