Fix minify app crash

-keep public class * extends android.preference.Preference

-keep public class com.android.vending.licensing.ILicensingService

# Keep Carrot templating engine

-keep class au.com.codeka.carrot.** { *; }

-keepclassmembers class au.com.codeka.carrot.** { *; }

-keepclasseswithmembers class * {

    native <methods>;

}