* restore permission request popup previously removed in #2486
* use legacy file picker in cases where saf file picker is not available
* fix missing file check logic in prepareSelectedDownload method (DownloadDialog.java)
-[#919] Fixed custom notification does not trigger unlocking on lockscreen.
-[#947] Fixes player crashing on internet outage, issue partially addressed.
-Fixed main player losing state after destroy while in background.
-Fixed main player controls not hiding automatically after orientation change.
-Fixed dialog uploader not marqueeing when too long.
-Fixed popup permission throwing NPE on BaseList.
-Refactored popup permissions to start in NavigationHelper.
-Extracted hardcoded string for player menus.
-Bump Java version to 1.8.
-Some lambda conversions.
* Fix permission at some places
* Fix access problem for downloaded files with external player
* Store finished Downloads
* Remove binding to DownloadService just to download a file
* Javadoc
* Code improvements
