Settings activity and rotation - Version 0.10

Big changes! Although most are internal changes to make sure that everything works as it should, there are a few notable UI changes.

This release also marks a before and an after with version numbers, taking advantage that the version number is now 1000, future updates will increment it by one instead mimicking the version name. Starting at v0.9 was a mistake, but now we have an excuse to make up for it!

New features:

• New settings activity thanks to the tremendous work of @gsantner. Big thanks!
• You can synchronize multiple repositories at once now!
• New activity to peek translations. If you're good at several languages, you can now check how some string has been translated into other languages very easily.
• Farewell, progress dialogs! Now everything fits perfectly within the UI, so nothing blocks you from using the application while some other task is running.

Bug fixes and enhancements:

• Rotation should work.
• Scanning cloned repositories through GitSource should be less IO heavy.
• Applications using an icon name dependent on the configuration are more prone to have their icon found now.
• Stringlate's website is now linked when making a pull request, so that people know what Stringlate is about.
• The progress shown on the discover activity is now more accurate.

Deprecation:

• Repositories older than v0.9.5 will no longer work, so upgrade to a previous version if you haven't updated for a really long while.

Updated translations:

• Polish by @9Cube-dpustula
• Russian by @accuman

Internal changes:

• A new Java interface has been created to ease creating other "sources" for strings. Like before, only a GitSource is available, but this should make it easier to implement other sources.
• Lint should be happier. For now.
• Farewell, ListView! Now a more efficient (and cleaner code) RecyclerView is used.