[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.
Add Utf8Utils.h/.cpp with class for UTF-8 string manipulations
RegExp: put more data to log on UTF-8 errors
[url] don't run ValidatePath() on hostnames where the protocol has an encoded hostname. fixes #14699
[osx/ios/atv2] - sync xcode project
[depends] update PCRE version, use new configure flags
[depends] update PCRE version for native tools
[epg] fix: incorrect timeline grid for first program of channels (Trac
#11479)
[Fix][Util] Allow any combination of flags, e.g., forced and default, for external subtitles.
[dxva] fixup: anaglyph 3d
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
[lang] update of internal addon language files
[lang] update of core language files
[lang] update of skin.confluence language files
videodb: fix SQL query in CleanDatabase() not considering NULLed fields
[Confluence] cosmetics
[rbp/omxplayer] Fix leak when playing multiple files from playlist

When omxplayer plays a second file from a playlist (i.e. without being shut down) a clock component gets leaked.
Eventually enough of these leaked components will stop further playback