[CHANGELOG] Add glium update
Include a word about WINIT_HIDPI_FACTOR=1.
Keep redirection.
- Rename `ImGuiCol::ChildWindowBg` to `ImGuiCol::ChildBg`.
Keep redirection.
+- Upgrade glium to 0.22.0. This updates winit to 0.16. This changes the way
+HIDPI are calculated. Depending on your needs, you may want to set HIDPI to 1
+by setting the environment variable `WINIT_HIDPI_FACTOR=1` if you use X11.
### Deprecated
