New shared preference, and settings activity, for the user to choose a "light" or "dark" theme
When MainActivity starts, it checks the shared prefs theme. If it doesn't match the app compat "night mode", then it sets the night mode accordingly and restarts the activity.
When the user changes the theme in the settings screen, the app is restarted to use the new theme.
Vector drawables now refer to color resources
Override a couple of color resources in the values-night/colors.xml file
Unrelated to this feature:
Fixed the background selector of the R, T, D icons.
Fixed crash on older devices when opening the About screen
values-night/colors.xmlfileUnrelated to this feature: