Add dark theme

[Nuntius0]

Adds a dark theme, addressing #3.

Per default it will follow the system theme (on systems that support it, else be white).
This includes definitely Android Q and LineageOS 16, but possible others (Funny enough not OxygenOS even though OnePlus prides itself with being on the forefront of these things!).

Note that I bumped minSdkVersion to 21 (i.e. from KitKat to Lollipo) in order to set the colour of the up arrow in the toolbar (via the android:colorControlNormal attribute in the styles.xml. Hope it's okay to drop support for a 6 year old Android version.

I also added action bars to the settings and about activities as well as icons to the preference items.

Known issues:

• When changing the theme to Follow system this is only applied after an app restart. I could not figure out why that's the case.

Tested on:

• LineageOS 16
• OxygenOS 9.5.8

EDIT: Made it really black instead of grey, dear OLED users! Haven't updated the screenshot though.

[ronidee]

Hello,

I've looked into the issue after you mentioned and found this answer at stackoverflow.
This app isn't using AndroidX yet. Migrating to AndroidX fixes this issue, I tested this with LOS-17.1 🙂

I was implementing the same thing, then saw already submitted a pull request. 👍 Things I miss are the undo-snackbar and renaming lists. You got that done too, or do I have to actually do this myself? 😁😂

[ronidee]

I also noticed that you forgot to update the parent theme for AppDialogTheme and AppAlertTheme, causing TextInputDialogs to be barely readable.
Replacing updating line 33 and 43 with DayNight fixes that.

[Nuntius0]

I also noticed that you forgot to update the parent theme for AppDialogTheme and AppAlertTheme, causing TextInputDialogs to be barely readable.

That should already be the case, I'm not sure why you're seeing something different?

Things I miss are the undo-snackbar and renaming lists.

I did undo snackbars in #55, but not renaming :)

Regarding androidx: Great that you found the culprit!
The migration is really quick with Android Studio. However all the other branches/PRs will need to be updated as well, so I see two options:

1. Migrate to androidx, then rebase+fix all the PRs individually and merge them when they're ready
2. Merge the PRs then migrate to androidx

Option 2) will be less work for everyone involved I think. In any case, I'll wait till @woefe signals that he has time to go through all of it.

[ronidee]

I'll wait till @woefe signals that he has time to go through all of it.

Not sure if he still maintains this repo? I'm just using your PR in my fork and added the renaming thing.
Also with some changes in the theme, I don't like green 😋.

2. Merge the PRs then migrate to androidx

Yes, that would be the best I think.

[PanderMusubi]

@woefe are you still maintaining this app? It has a lot of good feedback in terms of suggestions and PRs. If you don't have the time, perhaps please consider adding one of the contributors as admin so a new version can be released and published on F-Droid.