Set Navigation bar to black on dark themes

[qduff]

Uses the android:statusBarColor property to make the navigation bar black on dark themes. Without this it's white, at least on my phone.

Before:

After:

Also:

• Downgrades the minSdkVersion to 21 as there is I nothing that needs a greater version (I think!)
• Merges the values-v21/themes.xml into the normal themes.xml given minSdkVersion is equal to it.

Thanks :)

[paroj]

minSdk was at 24 because of some link errors: ac22ada

however CI passes. Will verify it locally later, but it seems to work now.

[qduff]

Hmm I think you're right - I've taken another look and this fork has a few uses the Java stream API, which is only supported in Java 8 (API level 24 onwards). I assume this would cause crashes on older devices.

I'll be honest I'm not that familiar with Android development, and I'll test it myself later to confirm, but I think you can also get around this with https://developer.android.com/studio/write/java8-support - though it might not even be worth supporting these old devices.

IMO the dark navigation bar commit is still worthwhile, and If you prefer I can remove the other commit in the meantime.

Thanks

[paroj]

yes, please drop the minSdk change for now then