* migrate few annotations to androidx
* mission recovery: better error handling (except StreamExtractor.getErrorMessage() method always returns an error)
* post-processing: more detailed progress
[file specific changes]
DownloadMission.java
* remove redundant/boilerplate code (again)
* make few variables volatile
* better file "length" approximation
* use "done" variable to count the amount of bytes downloaded (simplify percent calc in UI code)
Postprocessing.java
* if case of error use "ERROR_POSTPROCESSING" instead of "ERROR_UNKNOWN_EXCEPTION"
* simplify source stream init
DownloadManager.java
* move all "service message sending" code to DownloadMission
* remove not implemented method "notifyUserPendingDownloads()" also his unused strings
DownloadManagerService.java
* use START_STICKY instead of START_NOT_STICKY
* simplify addMissionEventListener()/removeMissionEventListener() methods (always are called from the main thread)
Deleter.java
* better method definition
MissionAdapter.java
* better method definition
* code cleanup
* the UI is now refreshed every 750ms
* simplify download progress calculation
* indicates if the download is actually recovering
* smooth download speed measure
* show estimated remain time
MainFragment.java:
* check if viewPager is null (issued by "Apply changes" feature of Android Studio)
* OggFromWebMWriter: rewrite (again), reduce iterations over the input. Works as-is (video streams are not supported)
* WebMReader: use int for SimpleBlock.dataSize instead of long
* Download Recovery: allow recovering uninitialized downloads
* check range-requests using HEAD method instead of GET
* DownloadRunnableFallback: add workaround for 32kB/s issue, unknown issue origin, wont fix
* reporting downloads errors now include the source url with the selected quality and format
* use Java I/O (classic way) on older android versions
* use Storage Access Framework on newer android versions (Android Lollipop or later)
* both changes have the external SD Card write permission
* add option to ask the save path on each download
* warn the user if the save paths are not defined, this only happens on the first NewPipe run (Android Lollipop or later)
* implement socket timeout error
* use 128k buffer size for copy
* use NewPipe HTTP user agent in the downloads
* automatically recover downloads with network errors that are queued
* replace "In queue" to "Pending" in the downloads header to avoid confusions (all languages)
* use 29bits Clusters size to support huge video resolutions (fixes#2291) (WebmWriter.java)
* add missing changes to WebmMuxer.java (i forget select the audio track)
