[coreSubs] restore default subtitle offset
ffmpeg: add osx fix, bump to 2.2.2
[addons] set Gotham repo to minimal 13.0.0 version
[addons] add Helix repo
Merge pull request #4721 from MartijnKaijser/helix_repo

Helix repo
[win32] clean up win32 installer
Merge pull request #4644 from MartijnKaijser/cleaninstall

[win32] clean up win32 installer
Merge pull request #4698 from FernetMenta/ffmpeg

ffmpeg: add osx fix and bump to 2.2.2
[osx/ffmpeg] disable spew of sdl compile/link flags
Merge pull request #4692 from Memphiz/fix-disabled-ffplay

[osx/ffmpeg] disable spew of sdl compile/link flags
Merge pull request #4683 from amet/restore_subs_delay

[coreSubs] restore default subtitle offset
videoplayer: adapt lateness detection and dropping to buffering
video player: present correct pts to user for a/v sync (after buffering in renderer)
videoplayer: some rework and documentation
renderer: bump buffers to 5
videoplayer: update frametime, it might change due to fps detection
videoplayer: give streams with invalid fps a chance for fps detection
dvdplayer: allow rewinding at end of stream, do a seek after rewind
dvdplayer: observe pts counter overflow
dvdplayer: avoid short screen flicker caused by unnecessary reconfigure of renderer