Summary:
new logout effect: it's just a slow fade in of the logout
greeter (window is usable immediately tough
Test Plan: logout greeter now fades in without setting the window opacity manually
Reviewers: graesslin, #plasma
Reviewed By: graesslin, #plasma
Subscribers: broulik, plasma-devel, kwin, #kwin
Tags: #plasma
Differential Revision: https://phabricator.kde.org/D5045
