Fix the issues with entvalidate.py
It doesn't properly handle mixins / special templates
On python 3.8+, XML elements are no longer sorted and this fails validation against entity.rng
mixins are not properly applied because the | split is incorrect (3 max items instead of 2)
merge="" is not supported
Parents aren't always passed when they should be.
on windows it is incorrectly assumed that the encoding is 1252
Patch by: @baco
Tweaks by: @Stan
Based on a patch by: @wraitii
Differential Revision: https://code.wildfiregames.com/D4698
git-svn-id: https://svn.wildfiregames.com/public/ps/trunk@27161 3db68df2-c116-0410-a063-a993310a9797