[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.
[confluence] texture changes for epg timeline view
videodb: shorten text for unavailable source popup during library clean
Merge pull request #3735 from xhaggi/confluence-epg-timeline

[confluence] texture changes for epg timeline view
Merge pull request #3629 from xhaggi/subtitle-flags

[confluence] replace subtitle flag icons with new ones
[WIN32] avoid getting the viewport so often.
[WIN32] fixed: use backbuffer only if we got it.
Merge pull request #3747 from wsoltys/viewport

[WIN32] avoid getting the viewport so often
[WIN32] removed CStdString from RenderSystemDX.*
fixed: compiler warning
AE: fix hidden setting stereo upmix if spdif is selected
AE: allow channel BC to be mixed into BL/BR os SL/SR
ActiveAE: let sink do channel mapping for 7.1
AESinkAlsa: Use 51Wide and 71Wide Maps when we need to do so