[confluence] replace subtitle flag icons with new ones

As discussed in #3552, this replace the subtitle flag icons with new
32x32 pixel icons from https://www.gosquared.com/resources/flag-icons/

This also fixes some wrong flags like uk. It's Ukrainian not United
Kingdom.
players: move more things into info structures for audio/video
dvdplayer: don't constantly hammer demuxer to get stream count

Note this could cause regressions in files where streams show
up during playback, but i think the demuxer signals such
situations now.
Add Utf8Utils.h/.cpp with class for UTF-8 string manipulations
RegExp: put more data to log on UTF-8 errors
[osx/ios/atv2] - sync xcode project
[depends] update PCRE version, use new configure flags
[depends] update PCRE version for native tools
videodb: make sure to return the same playcount (0 or 1) for tvshows (fixes #14703)
[epg] fix: incorrect timeline grid for first program of channels (Trac
#11479)
Merge pull request #3691 from Montellese/tvshows_playcount

videodb: make sure to return the same playcount (0 or 1) for tvshows (fixes #14703)
[Fix][Util] Allow any combination of flags, e.g., forced and default, for external subtitles.
don't constantly hammer demuxer to get stream count

Note this could cause regressions in files where streams show
up during playback, but i think the demuxer signals such
situations now.
Merge pull request #3663 from elupus/dvdlocks

Some cleanups in gui/player callbacks
CharsetDetection::GetBomEncoding: fix: remove unused leftover parameter
StringUtils::TrimLeft: fix: if string contains only trim chars then string must be erased instead of left untouched
fix addon uninstall yesno dialog behaviour

introduced in 333025f

addon uninstall yesno dialog behaviour is broken:
yes = does nothing. no = uninstalls the addon
Merge pull request #3700 from stefansaraev/fixaddons

fix addon uninstall yesno dialog behaviour
[pvr] fix: no channel numbers in channel-osd if continue last channel
allow access to special://skin through the webserver's VFS handler