Ship proguard consumer config

[grote]

This makes the life of users of this library easier, because their app won't crash when using proguard.

By embedding a ProGuard file in your library module, you ensure that app modules that depend on your library do not have to manually update their ProGuard files to use your library.

See https://developer.android.com/studio/projects/android-library#Considerations

[grote]

This seems to do the trick:

-keep class org.torproject.jni.** { *; }

[eighthave]

Sounds good to me. My experiences with proguard have always left me mystified as to what is actually going on, so I don't feel qualified to take it on.