bug#51404: Support system dark mode on Windows 10

[Vince Salvino]

Update: I managed to get my hands on an 1809 system and was able to get dark 
mode working there as well. As far as I can tell 1809 is the absolute minimum 
as that is when this setting and dark mode Explorer were introduced into 
Windows.

The advantage is that this will now work on Windows Server 2019 and Windows 
LTSC 2019, which some folks may be limited to as those are the latest Server 
and LTSC releases.

Attached patch includes the complete change, with relevant notes etc.

Vince Salvino

0001-Support-system-dark-mode-on-Windows-10-version-1809-.patch
Description: 0001-Support-system-dark-mode-on-Windows-10-version-1809-.patch