Refs #2096: The theme selector now controls all colors

Previously, if the system preference was dark mode and the user
explicitly selected the light theme, the @media block still interferred
with the styling. This is fixed by only evaluating the color scheme
preference when initializing the toolbar and later only looking at our
own selected theme.

Also, removed the DEFAULT_THEME setting; falling back to system defaults
seems much better to me.

Author: matthiask

debug_toolbar/settings.py

@@ -45,7 +45,6 @@
     "TOOLBAR_LANGUAGE": None,
     "IS_RUNNING_TESTS": "test" in sys.argv,
     "UPDATE_ON_FETCH": False,
-    "DEFAULT_THEME": "auto",
 }