AE: add settings to enable ac3 transcode and upmix via ac3 transcoding
ActiveAE: implement settings for ac3 transcode and upmix
AE: rename setting speaker configuration
Merge pull request #4025 from FernetMenta/audiopage

AE: add settings for ac3 transcode and ac3 upmix
fixed: Only force cache for video else it may cause a thread-storm
Merge pull request #4027 from arnova/file_cache_not_for_all_fix

fixed: Only force cache for video else it may cause a thread-storm
changed: Enable multicache for mkv files (fixes #13841)
changed: We should always check for multistream when caching
Merge pull request #3963 from arnova/mkv_multi_cache

changed: Enable multicache for mkv files (fixes #13841)